Article

Effect of Novel Maize-based Dietary Fibers on Postprandial Glycemia and Insulinemia

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Abstract

Postprandial hyperglycemia has been associated with increased oxidative stress and the development of diabetes, heart disease and all-cause mortality. To assess the effect of novel maize-based dietary fibers on postprandial glycemia and to assess the correlation between a rapid in vitro digestibility system and the blood glucose response. In a clinical study, 12 healthy volunteers were fed seven test beverages containing maize-based fiber ingredients (25g total carbohydrate) along with 2 control meals on separate occasions in random order. Capillary blood samples were obtained and the relative glycemic and insulinemic responses were assessed by calculating the incremental area under the 2 h blood response curves. In vitro digestibility studies of the test fibers and control were also undertaken to determine if these correlated with the clinical findings. All test fibers resulted in significantly lower glycemic and insulinemic responses for the incremental area under the curve (iAUC) and at all time points compared with the control (P < 0.05). The in vitro digestibility curves were comparable to the cumulative in vivo iAUCs. In vitro data expressed as percent digestion correlated significantly with the in vivo iAUC for the first 30min of the test meal (P < 0.05). These novel maize-based dietary fibers all produce lower postprandial glycemic and insulinemic responses than the control. While further assessment is necessary in beverage and foods containing these fibers, they may be effective in applications for dietary strategies to control diabetes and other chronic diseases. In addition, the in vitro digestibility assay correlated well with in vivo data and may be useful in guiding product development.

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... The SCF used in both sets of blends demonstrated a resistance to hydrolytic digestion, with SCF having an increased resistance compared with SCFsd (29 vs. 50% digestible, respectively). Kendall et al. (2008) evaluated a SCF similar to the ones used in the blends and reported the in vitro digestibility was 14.5%, which is less than either of the SCFs tested in the current study. Differences in production methods likely affected digestibility of the different SCFs evaluated. ...
... The ability of the SCF to resist hydrolytic digestion was due, in part, to the linkages found in their molecular structure. The presence of α-1,6 glycosidic linkages and inaccessibility of the α-1,4 linkages increase digestive enzymatic resistance in SCF (Kendall et al., 2008). Blending pullulan with either of the SCF resulted in increased released monosaccharide concentrations, especially glucose. ...
... These factors likely contributed to SCFs ability to attenuate blood glucose concentrations more than SCFsd. Kendall et al. (2008) evaluated the glycemic response in humans of SCF incorporated into a beverage. Authors reported an area under the curve of 28.5 mmol/L, which was similar to the area under the curve (39.1 mmol/L) of SCF reported in the current study. ...
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The objective of these experiments was to measure in vitro hydrolytic digestion and glycemic and insulinemic responses of select carbohydrate blends, all containing the novel carbohydrate, soluble corn fiber (SCF). Two SCF that varied in their method of production were used to formulate the carbohydrate blends. One set of blends contained a SCF that was spray-dried (SCFsd), then blended with different amounts of either pullulan, sorbitol, or fructose. The other set of blends contained a SCF produced using longer evaporation time (SCF), then blended with different ratios of pullulan, sorbitol, and fructose. Free sugar concentrations found in the individual SCFsd and SCF substrates were low, but varied. Spray-dried soluble corn fiber had a lower free sugar concentration compared with SCF (2.8 vs. 14.2%). Glucose was the main free sugar found in both SCFsd and SCF, but at different concentrations (2.7 vs. 12.7%, respectively). The majority of the SCFsd blends were completely hydrolyzed to their monosaccharide components. Glucose accounted for most of the hydrolyzed monosaccharides for SCFsd and all the SCFsd blends. Hydrolyzed monosaccharide concentrations for the SCF:pullulan:sorbitol:fructose blends followed similar trends to the SCFsd blends where greater percentages of fructose and sorbitol resulted in lower hydrolyzed monosaccharide concentrations. The SCFsd blends had intermediate to high amounts of monosaccharides released as a result of in vitro hydrolytic digestion. The SCFsd:pullulan blends were more digestible in vitro (approximately 91%; P < 0.05) than SCFsd:fructose or SCFsd:sorbitol. Total released monosaccharides were high in SCFsd blends containing either 50% fructose or sorbitol, but the combination resulted in lower concentrations of glucose released (P < 0.05). The SCF:pullulan:sorbitol:fructose blends also had intermediate to high released monosaccharides as a result of in vitro hydrolytic digestion. All SCF blends resulted in lower glycemic and insulinemic responses compared with the maltodextrin control (P < 0.05) using a canine model. The addition of pullulan reduced the glycemic response compared with maltodextrin at all concentrations, but only 50:50 SCFsd:pullulan resulted in a lowering of the glycemic response compared with SCFsd alone (P < 0.05). The addition of fructose and sorbitol in the blends had the greatest impact on glycemic and insulinemic responses, even at concentrations as low as 5% of the blends. Overall, SCF and their blends may prove beneficial as components of low glycemic foodstuffs.
... The low small intestinal digestibility of carbohydrates in novel fiber sources reduces postprandial glucose and insulin responses in humans and dogs, which may be beneficial in diabetic management. 5,6 Fermentation of carbohydrates in the large bowel may also increase the absorption of short-chain fatty acids, which may have benefits in controlling colonic diseases. 7 The reduced absorption of energy as glucose in the small intestine may also reduce the bioavailable energy of novel fiber sources compared with foods rich in starch, which may assist in weight management. ...
... Soluble corn fiber is a product of corn starch hydrolysis, which has an average degree of polymerization of 10. 13 Pullulan is a polysaccharide that is produced via fermentation by Aureobasidium pullulans. It has a degree of polymerization of 3000 and a molecular weight of 486 000 Da. 5,13 The four novel fiber ingredients were supplied by Tate and Lyle (Decatur, IL, USA). Both RS 60 and SCF 70 are commercial products marketed under the PROMITOR brand name. ...
... By the analytical method used (AOAC 991.43), 17 the TDF content of SCF 70 was 100 g kg −1 , although if the analytical method AOAC 2001.03 is used, 25 SCF 70 contains 700 g kg −1 TDF. 5 The TDF concentration in the novel fiber ingredients ranged between 629 and 854 g kg −1 . The GE concentration in the novel fibers was between 15.6 and 16.1 MJ kg −1 , and the DM concentration was between 901 and 948 g kg −1 . ...
Article
Consumption of different dietary fibers may influence the digestibility of carbohydrates and other nutrients. Therefore, the objectives of this experiment were to determine the effect of novel fiber ingredients on the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), crude protein (CP), and total dietary fiber (TDF) in pigs, and to calculate the standardized digestibility of analyzed TDF in four novel fiber ingredients. The AID of DM and GE in diets containing novel fiber ingredients were less (P < 0.05) than in a maltodextrin diet. Addition of cellulose or pullulan, but not resistant starch (RS) 60, RS 75, or soluble corn fiber 70 reduced (P < 0.05) the AID of CP. The average ileal and total tract endogenous losses of analyzed TDF were calculated at 25.25 and 42.87 g kg(-1) DM intake, respectively. Addition of novel fiber ingredients to a maltodextrin based diet had different effects on the AID of DM, CP, GE, and TDF. Measurements of the standardized digestibility of analyzed TDF may be a better indicator of TDF fermentability than measurements of AID and ATTD of TDF because some endogenous metabolites may be analyzed as TDF.
... Epidemiological evidence of the health benefits of dietary fiber has prompted both the health and food sectors to incorporate dietary fibers into a variety of food products. Despite a range of studies on the health benefits of dietary fiber, considerable research has emerged in the past decade or so [15][16][17][18] on the health benefits of soluble corn fiber (SCF). SCF have also been shown to have higher digestive tolerance [19]. ...
... A previous study tested the glycemic and insulin response of healthy adults to soluble corn fiber using a total replacement method, i.e., 25 g glucose replaced with 25 g soluble corn fibre. In that study, only 12 participants were sufficient to detect significant reductions in postprandial glucose and insulin [17]. Due to different study design used in this current study, i.e., only partial replacement of glucose with soluble corn fibre, the effects are predicted to be smaller, and we hence anticipate that 19 participants will allow us to detect a clinically meaningful effect of d = 0.7 (medium to large effect size) using a crossover study design at 80% statistical power and alpha = 0.05. ...
... The position of the predominant glycosidic linkages is known to contribute to the low digestibility of SCF. Kendall CW et al. [17] evaluated the in vitro digestibility of SCF, and it was reported to have a digestibility of 14.5%. Ropert, et al. [30] suggested that the short-chain fatty acids produced by colonic fermentation of carbohydrates may also be a meditator of gastric motility. ...
Article
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Increasing prevalence of type 2 diabetes mellitus (T2DM) in Asia has prompted the exploration of dietary fibers as an ingredient to attenuate glycemic response (GR). This study aims to compare the effects of replacing 50% of total carbohydrate with soluble corn fiber (SCF) or maltodextrin on the GR and insulin response (IR). In this randomized cross-over study, twenty-two healthy Chinese males aged between 21–60 years were recruited. The participants consumed glucose beverages and four test meals comprising SCF or maltodextrin in glutinous rice or as a drink. Repeated-measure ANOVA was used to compare the incremental area under the curve values of glucose (iAUGC) and insulin (iAUIC) of all the foods. Relative response (RR) of the beverages were also calculated and compared using paired t-test. SCF treatments had significantly lower iAUGC (p-value < 0.05) and iAUIC (p-value < 0.001) as compared to all treatments. Both treatments (rice and beverage) of maltodextrin were not significantly different from glucose (p-value > 0.05). Maltodextrin beverage had significantly increased postprandial GR and insulin secretion by 20% and 40%, respectively, when compared to SCF beverage (p-value < 0.001). This study shows that the inclusion of SCF into the diet is beneficial in controlling the postprandial GR. Replacing total carbohydrates with SCF effectively lowers GR and IR.
... During the production of the SCF, different acid and enzyme combinations were utilized to form glycosidic linkages, predominantly α-1,6 linkages, among monosaccharides in the corn syrup to produce a more digestionresistant carbohydrate. Kendall et al. (2008) evaluated the in vitro digestibility of an SCF that was similar to G2-SCF-phos+HCl (Lq1). The SCF was calculated to be 14.5% digestible, which is less than the 28% digestibility that was measured in the current study. ...
... The RGR data followed the same pattern, with Malt resulting in the greatest (P < 0.05) value and the SCF resulting in intermediate values (average RGR of 44%). Kendall et al. (2008) evaluated the glycemic response in humans of a SCF that was similar to G2-SCF-phos+HCl (Lq1) and incorporated into a beverage. Authors reported an AUC of 28.5 mmol/L, which was similar to the AUC (39.1 mmol/L) found in the current study. ...
Article
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The objective of this research was to measure in vitro hydrolytic digestion, glycemic and insulinemic responses in dogs, and true ME (TMEn) content of select soluble corn fibers (SCF) in roosters. The first generation (G1) SCF included hydrochloric acid-treated corn syrup (G1-CS-HCl), an SCF with an increased total dietary fiber (TDF) content (G1-SCF-HCl), an SCF that was spray-dried (G1-SCF-SD), and a hydrogenated SCF (G1-SCF-hydrog). The second generation (G2) SCF included those prepared using phosphoric acid catalyzation in both a liquid [G2-SCF-phos (Lq)] and powder [G2-SCF-phos (Pw)] form, and SCF that were prepared using hydrochloric acid catalyzation in both a liquid [G2-SCF-HCl (Lq)] and powder [G2-SCF-HCl (Pw)] form. Also, in the G2 set of samples were SCF prepared using the same method, but in 3 separate batches, all of which contained 70% TDF and 15% sugars. Two were in liquid form [G2-SCF-phos+HCl (Lq1)] and [G2-SCF-phos+HCl (Lq2)], and one in powder form ([G2-SCF-phos+HCl (Pw)]. A lower sugar form (80% TDF and 5% sugar) of SCF was also evaluated (G2-SCF-low sugar). Glucose was the major free sugar and bound monosaccharide in all SCF except for G1-SCF-hydrog that had greater concentrations of sorbitol. All SCF had intermediate to low amounts of monosaccharides released as a result of in vitro hydrolytic digestion, with glucose being the primary sugar component released. The G1-SCF were more digestible in vitro (approximately 50%) compared to G2-SCF (approximately 32%). All SCF had attenuated glycemic responses in adult dogs compared to a maltodextrin control (P < 0.05). The G2-SCF, on average, had lower glycemic responses and TMEn values in roosters than G1-SCF. All SCF had low free sugar concentrations with varying degrees of resistance to digestion, reduced caloric content, and attenuated glycemic and insulinemic responses in adult dogs. These ingredients are potential candidates for inclusion in reduced calorie and low glycemic canine diets.
... The RS 60 and RS 75 used in this experiment are type 3 RS that are retrograded starch and have highly crystalline structures that makes them resistant to enzymatic digestion. 26 This resistance to digestion was reflected in the small amount of glucose that was released in the in vitro assay from RS 60 and RS 75. However, resistant starches are known to be highly fermentable 27 and may, therefore, provide additional calories through fermentation. ...
... The predominance of α-1,6 glucosidic linkages and the presence of some α-1,2 and α-1,3 glucosidic linkages in SCF 70 also makes SCF 70 resistant to digestion. 26 However, the lack of a crystalline structure in SCF 70 is likely the reason why the results of the in vitro method were closer to the caloric value obtained in the in vivo experiments than results for RS 75. ...
Article
The objective of this study was to compare two in vivo methods using pigs and roosters and an in vitro method for determining the caloric value of four fiber sources [i.e., two resistant starches (RS 60 and RS 75), soluble corn fiber (SCF 70), and pullulan]. Metabolizable energy (ME) in pigs and true metabolizable energy (TMEn) in roosters were determined by using 72 barrows and 24 roosters, respectively. A two-step in-vitro procedure was used to quantify monosaccharides released. Results of the two in vivo experiments corresponded well with RS 75 having the least caloric value (7.55 MJ/kg in pigs; 6.19 MJ/kg in roosters) and pullulan having the greatest caloric value (12.21 MJ/kg in pigs; 13.94 MJ/kg in roosters). The caloric values for all the fiber ingredients were less (P < 0.05) than in MD both in pigs and in roosters. Despite some limitations, results of the in vitro procedure corresponded well with the in vivo experiments where the concentration of glucose hydrolyzed from RS 60, RS 75, and SCF 70, but not pullulan, was less (P < 0.05) than the concentration of glucose hydrolyzed from MD. However, the greatest accuracy was obtained in the in vivo experiments.
... The relative glycemic response (average 84%) of the Nutriose SFDs (C2 and C3) evaluated were higher than what has been reported for a wheat Nutriose SFD in humans with a lower RGR of 25% (30,31). A tapioca-based SFD similar to T1 and T2 was evaluated in humans and resulted in a similar RGR value as what was found using the canine model (48.2 and 51.6, respectively) (32). ...
... These results are in comparison to a RIR of 13% reported for a wheat-based SFD in humans (30,31). A tapioca-based SFD resulted in a somewhat similar RIR in humans as T2 in this experiment (40.2 and 50.5, respectively) (32). The attenuated blood glucose peaks do not induce high insulin secretion resulting in low insulin response values for the SFDs. ...
... 7 Soluble corn fibre forms first through exposing corn syrup to a suite of pancreatic and brush border enzymes for 48 h or more, which leaves a stream of sugars and digestion-resistant carbohydrates. 3 This syrup is then filtered repeatedly until the substance is composed of virtually all non-digestible fibres. 8,9 Numerous companies and nutrition products include and list both IMO and SCF as fibre sources. However, to date, research has not examined the comparison of these two carbohydrates in vivo in the same setting. ...
... Consequently, these results agreed with that of Kohmoto et al. 4, who found that IMO were nearly 85% digested. Moreover, Cervantes-Pahm et al. 8 and Kendall et al. 9 found virtually no digestion in SCF, both in vivo and in vitro. ...
Article
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Dietary fibre refers to nutrients in the diet that gastrointestinal enzymes do not digest. If properly labelled, dietary fibres should not significantly elevate blood glucose or insulin and should ferment in the large intestine. Because of the recent rise in low-carbohydrate products on the market, consumers use these various fibres without adequate knowledge concerning whether or not these ingredients affect any blood parameters and constitute a dietary fibre. The aim of this study was to examine the impact of isomaltooligosaccharides (IMO) as compared to soluble corn fibre (SCF) consumption on blood glucose, insulin and breath hydrogen responses in healthy young men and women. After an overnight fast, nine individuals consumed 25 g of either placebo (PLA), IMO or SCF. Breath hydrogen was significantly higher in the SCF condition than in the IMO and PLA at 90, 120, 150 and 180 min (p < 0.0001). Blood glucose and insulin were higher in the IMO condition (p < 0.0001) at 30 min compared to the SCF or PLA conditions, which were not significantly different from each other. These data suggest that IMO does not constitute a dietary fibre and instead should be explored as a slow-digesting carbohydrate.
... Tate & Lyle, Decatur USA, has developed this new type of resistant starch and markets them under the name of Promitor TM RS60 and RS75. Both resistant starches were shown to lower glycemic and insulin responses, compared to glucose and soluble fibers, in healthy volunteers (Kendall et al., 2008). ...
Article
Starch is an agricultural raw material used in many food and industrial products. It is present in granules that vary in shape in the form of amylose and amylopectin. Starch-degrading enzymes are used on a large scale in the production of sweeteners (high fructose corn syrup) and concentrated glucose syrups as substrate for the fermentative production of bioethanol and basic chemicals. Over the last two decades α-glucanotransferases (EC 2.4.1.xx), such as branching enzyme (EC 2.4.1.18) and 4-α-glucanotransferase (EC 2.4.1.25), have received considerable attention. These enzymes do not hydrolyze the starch as amylases do. Instead, α-glucanotransferases remodel parts of the amylose and amylopectin molecules by cleaving and reforming α-1,4- and α-1,6-glycosidic bond. Here we review the properties of α-glucanotransferases and discuss the emerging use of these enzymes in the generation of novel starch derivatives.
... However, other studies have reported a lower glucose response when PDX was incorporated into chocolates, sweetened dried cranberries and strawberry jam (35 -37) . Kendall et al. (11) postprandial glucose and insulin responses for SCF when given as a lemonade drink. These studies investigated postprandial glucose and insulin concentrations after consumption of a single meal over a limited period of time rather than those after consumption of two meals (breakfast and lunch containing PDX or SCF) during daytime as has been done in the present study. ...
Article
High-fibre diets offer several beneficial health effects. The objective of the present study was to investigate whether replacement of 30 % of the available carbohydrates with polydextrose (PDX) or soluble maize fibre (SCF) at breakfast and lunch would result in an increased fat oxidation rate and satiety, which may be of relevance for body weight control and diabetes prevention. In a single-blind, randomised cross-over study, eighteen overweight men and women underwent four different dietary interventions, which consisted of a PDX diet, a SCF diet and two control diets (full energetic and isoenergetic, comparable with PDX with respect to g or energy percentage of macronutrients, respectively). Glycaemic profile, energy expenditure and substrate oxidation were measured for 24 h in a respiration chamber. Circulating insulin, NEFA and TAG concentrations were determined over a 14 h period during daytime. Appetite ratings were assessed using visual analogue scales. The replacement of available carbohydrates with PDX or SCF reduced the peak glucose response, which was accompanied by reduced postprandial insulin responses. Moreover, higher concentrations of circulating NEFA were observed after consumption of both fibre diets, which were accompanied by an increased fat oxidation over 24 h. This effect was mainly attributed to the lower energetic value of the fibre diets and not to the fibres per se. Besides increasing fat oxidation, PDX exerted a pronounced suppressive effect on appetite ratings. The replacement of available carbohydrates with PDX may be of special interest because of its beneficial effects on metabolic profile and it may affect body weight control in the long term.
... While further assessment is necessary in beverage and foods containing these fibers, they may be effective in applications for dietary strategies to control diabetes and other chronic diseases. 55 The effect of Zea mays L. saponin (ZMLS) on ultrastructure of kidney and pancreas and blood glucose in the diabetes rats induced by streptozocin was studied. ...
Article
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Diabetes mellitus (DM) is a common disease affecting several million individuals worldwide. Over the last century, changes in human behavior and lifestyle have resulted in a dramatic increase in the incidence of diabetes world over. Though oral hypoglycemic agents and insulin are the mainstay of treatment of diabetes, they have prominent side effects and fail to significantly alter the course of diabetic complications. Lifestyle modifications including appropriate diet and exercise programs have been found to be greatly effective in the management of the disease. Diet therapy, especially, is showing a bright future in the therapy of DM. In particular, the commonly consumed cereal grains have been reported to possess antidiabetic properties. There are a variety of grains and grain products which can be beneficial in lowering glucose and insulin responses. The synergistic effect of several whole-grain components such as dietary fiber, phytochemicals, vitamin E, Mg, or others may be involved in the reduction of the risk for type 2 diabetes mellitus (T2DM). Hence, replacing low fiber grain foods such as white bread with whole grain higher fiber or higher amylose content products will reduce risk of developing insulin resistance and obesity and improve the health of the population.
... Some Native American corn products such as tortillas (54%) and hominy (57%) have much lower glycemic indices than white bread (Miller, 1995). Test beverages containing maize-based fiber ingredients (25-g total carbohydrates) fed to 12 healthy volunteers resulted in significantly lower glycemic and insulinemic responses for iAUC and at all time points compared with control (Kendall et al., 2008). ...
Article
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Over the last few decades life style changes have resulted in drastic increase in the incidence of diabetes all over the world especially in the developing countries. Oral hypoglycemic agents and insulin form the main stay in controlling diabetes but they have prominent side effects and fail to significantly alter the course of diabetic complications. Appropriate diet and exercise programs that form a part of lifestyle modifications have proven to be greatly effective in the management of this disease. Dietary therapy is showing a bright future in the prevention & treatment of diabetes. Cereal grains which form the staple diet for humans in most of the countries are increasingly being used to treat diabetes and other associated disorders in view of their antidiabetic and antilipidemic potential. Given this background, this paper reviews the possible mechanisms of lowering blood sugar and cholesterol levels possessed by various commonly consumed cereal grains. It is concluded that cereal grains are not only the potential sources of energy but also possess the therapeutic role in preventing the metabolic disorders and decreasing the risk factors for cardiovascular and renal disease.
... Ancient grains (amaranth, barley, millet, quinoa, sorghum, spelt, whole-wheat couscous) have higher fiber content than white rice [76]. Depending on the degree to which corn is processed, it may either provide sufficient fiber to lower postprandial glycemic and insulinemic responses [77], or it may have potential detrimental effects on glycemic control and diabetes when processed into refined corn flour, corn syrup and high fructose corn syrup [78,79], one of the main sweeteners used globally. Minimally-processed, whole kernel maize may be an appropriate alternative food in some cultures. ...
Article
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The prevalence of type 2 diabetes has been reaching epidemic proportions across the globe, affecting low/middle-income and developed countries. Two main contributors to this burden are the reduction in mortality from infectious conditions and concomitant negative changes in lifestyles, including diet. We aimed to depict the current state of type 2 diabetes worldwide in light of the undergoing epidemiologic and nutrition transition, and to posit that a key factor in the nutrition transition has been the shift in the type and processing of staple foods, from less processed traditional foods to highly refined and processed carbohydrate sources. We showed data from 11 countries participating in the Global Nutrition and Epidemiologic Transition Initiative, a collaborative effort across countries at various stages of the nutrition-epidemiologic transition whose mission is to reduce diabetes by improving the quality of staple foods through culturally-appropriate interventions. We depicted the epidemiologic transition using demographic and mortality data from the World Health Organization, and the nutrition transition using data from the Food and Agriculture Organization food balance sheets. Main staple foods (maize, rice, wheat, pulses, and roots) differed by country, with most countries undergoing a shift in principal contributors to energy consumption from grains in the past 50 years. Notably, rice and wheat products accounted for over half of the contribution to energy consumption from staple grains, while the trends for contribution from roots and pulses generally decreased in most countries. Global Nutrition and Epidemiologic Transition Initiative countries with pilot data have documented key barriers and motivators to increase intake of high-quality staple foods. Global research efforts to identify and promote intake of culturally-acceptable high-quality staple foods could be crucial in preventing diabetes. These efforts may be valuable in shaping future research, community interventions, and public health and nutritional policies.
... In fact, numerous authors have reported results in terms of fibre reducing glucose release obtained in both soluble and insoluble dietary fibres. In such reports, the authors have explained the effect of fibre in reducing starch degradation on the possibility of fibres coating starch granules and inhibiting enzyme penetration (Brennan et al., 1996;Anderson et al., 1999;Brennan et al., 2002;Brennan, 2005;Granfeldt et al., 2008) and the possibility that the viscous nature of fibres affects the efficiency of enzyme functionality (Jenkins et al., 2002;Flammang et al., 2006;Kendall et al., 2008;Aravind et al., 2012). It is probable that inclusion of DFs to the extruded snack products acts in a viscous-related manner in modulating starch digestion process (Brennan et al., 2012a,b,c). ...
Article
Two non-starch polysaccharides, guar gum and wheat bran, were used at 15% replacement level in a cereal base to produce an extruded breakfast cereal product from both wholemeal and high-ratio wheat flour mixes. The inclusion of the non-starch polysaccharides into the flour bases had no significant effect on the expansion ratio of the products. However, the product density and bulk density of the extruded products increased with guar gum and wheat bran addition. The pasting properties of the raw flour and polysaccharide base as well as the extruded products were altered with the incorporation of polysaccharides, with guar gum-enriched products showing elevated peak and final viscosity readings. This appeared to be related to moisture manipulation and hence the regulation of gelatinisation. In vitro starch hydrolysis of the raw bases and the extruded samples illustrated that the extrusion process significantly increased the availability of carbohydrates for digestion. Additionally, the inclusion of non-starch polysaccharides in the raw bases significantly reduced the rate and extent of carbohydrate hydrolysis. This potentially glycaemic reducing action was also evident in the extruded products where the incorporation of guar gum at 15% yielded a reduction of starch hydrolysis of 36% in the wholemeal base and 32% in the high-ratio white wheat flour base.
... Digestion over a 5-7 h period reduces postprandial glycemic and insulinaemic responses and increases the satiety period [116,117]. However Kendall et al. [121] reported that RS decreases the postprandial serum glucose level considerably within the first 120 min. Reader et al. [117] reported significantly lower blood glucose level in human subjects feeding on commercial RS3 ingredient (CrystaLean 1 ) as compared to those feeding on simple sugars, oligosaccharides, and common starch. ...
Article
Resistant starch (RS) encompasses those forms of starch, which are not accessible to human digestive enzymes and are fermented in the colon producing short chain fatty acids. Because of its unique physicochemical and functional properties resistant starch finds use in wide range of food products and yields high quality products. It has recently gained substantial importance due to its positive impact on health. Among the health benefits include improvement of colonic health and microflora, management of diabetes, lower glycemic index and blood cholesterol levels, reduced bilestone formation, increased mineral absorption and potential to modify fat oxidation. Technically RS can be produced by different physical, enzymatic and chemical modifications. This article reviews about types of resistant starch, sources, preparation, health benefits and applications of resistant starch.
... In fact, numerous authors have reported results in terms of fibre reducing glucose release obtained in both soluble and insoluble dietary fibres. In such reports, the authors have explained the effect of fibre in reducing starch degradation on the possibility of fibres coating starch granules and inhibiting enzyme penetration (Brennan et al., 1996;Anderson et al., 1999;Brennan et al., 2002;Brennan, 2005;Granfeldt et al., 2008) and the possibility that the viscous nature of fibres affects the efficiency of enzyme functionality (Jenkins et al., 2002;Flammang et al., 2006;Kendall et al., 2008;Aravind et al., 2012). It is probable that inclusion of DFs to the extruded snack products acts in a viscous-related manner in modulating starch digestion process (Brennan et al., 2012a,b,c). ...
Article
Consumer appeal for ready‐to‐eat (RTE) products is forecast to grow rapidly over the next 5 years as consumers demand convenient snacks with exciting sensory and textural properties. Extrusion technology has been used extensively in the production of cereal RTE snacks due to its ease of operation and ability to produce a variety of textures and shapes which appeal to consumers. Many of the existing RTE products are relatively high in sugar and salt, thus being regarded as energy dense but nutritionally poor foods. However, there exists a potential to manipulate the nutritional status of extruded RTEs by altering the digestion potentials of starch and protein, and by the incorporation of bioactive components such as dietary fibre. The review article explores some of the recent research in this field and illustrates opportunities by which the global food industry could react to consumers' requirements for healthful RTE snack products in the coming years.
... In different human trials, SGF has demonstrated a consistent low glycaemic response, approximately 30% of that of rapidly digestible carbohydrates (Kendall et al., 2008, with the amount of indigestible carbohydrates present in the test product. In addition, SGF has been shown to improve intestinal regularity by increasing stool weight and frequency at 20 g per day (Timm et al., 2011;Vester Boler et al., 2011). ...
Article
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Background: To assess consumers’ acceptance of a new fibre, it is essential to evaluate its digestive tolerance after ingestion. We aimed to determine the tolerance of increasing dosages of Promitor™ Soluble Gluco Fibre (SGF; Tate&Lyle, Hoffman Estates, IL, USA) up to 70 g fibre per day using a validated gastrointestinal composite score. Methods: A composite score of gastrointestinal tolerance integrating gastrointestinal symptoms, stool frequency and consistency was applied. To statistically validate this composite score, the gastrointestinal tolerance of inulin (10 g versus 20 g containing, respectively, 9 g versus 18 g of fibre) was assessed in 18 healthy volunteers in a randomised double-blind placebo-controlled cross-over study. Second, in a double-blind placebo-controlled cross-over study with 20 healthy volunteers, the gastrointestinal tolerance of SGF in both acute and ‘spread over the day’ conditions of consumption was assessed. Results: By contrast to 10 g, 20 g of inulin demonstrated a significant difference in composite score compared to placebo [P < 0.001, difference = 7.6; 95% confidence interval (CI) = 3.8–11.3]. These values were considered as reference during the second study. In acute conditions, 40 g of SGF fibre was the highest (threshold) dose tested that indicates the digestive tolerance criteria (difference from placebo on the composite score <7.6 and upper limit of the 95% CI <11.3); this is twice the amount tolerated for inulin. In ‘spread over the day’ conditions, 65 g of SGF fibre was the threshold dose (P < 0.001, difference = 6.5; 95% CI = 3.4–9.5). Conclusions: The results of the present study demonstrate that 40 g of SGF fibre, when consumed as a single dose, and 65 g of SGF fibre, when consumed in multiple-doses, across the day are well-tolerated by healthy volunteers.
... In previous acute studies where supplements were matched only by starch weight, the administration of RS was found to typically induce a reduction on the glycemic and insulinemic responses. These effects have been observed after providing 40 g of NBS, 50 g of raw potato starch, or 25 g of RS to healthy subjects [30][31][32]. In these experiments, the effects of RS on glycemia and insulin probably reflected the greater availability of digestible carbohydrates in the control group. ...
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Reports surrounding the role of resistant starch (RS) on postprandial lipemia in humans are scarce. The aim of the present study is to examine the effects of resistant starch on the postprandial lipemic response, subjective measures of appetite, and energy intake in overweight and obese subjects. In a randomized, single-blind, crossover study, 14 overweight/obese participants ate a high-fat breakfast (679 kcal, 58% from fat) and a supplement with native banana starch (NBS), high-amylose maize starch (HMS), or digestible maize starch (DMS) on three separate occasions. All supplements provided were matched by the available carbohydrate content, and the RS quantity in NBS and HMS supplements was identical. Appetite was estimated using visual analogue scale (VAS) and an ad libitum test meal. Postprandial glycemia, triglycerides, cholesterol, high-density lipoprotein (HDL) cholesterol, and insulin excursions did not differ between treatments. Subjective appetite measures of satiety were significantly increased after HMS; however, no effects on energy intake were observed during the ad libitum test meal. These findings suggest that a single acute dose of RS cannot be expected to improve postprandial lipemia in subjects with overweight or obesity on a high-fat meal. However, the potential benefits of long-term supplementation should not be ruled out based on these results.
... This result is in line with the expected, since pepsin has specific activity on proteins and not on lipids, act-ing by hydrolytic activity [20]. At intestine simulation conditions, the presence of pancreatin which is produced by exocrine cells of porcine pancreas to digest lipids, i.e., has lypolitic activity, was important for RA release from SLN [21], since promoted SLN disaggregation and consequently RA release. This lipase splits the ester linkages and releases partial glycerides or glycerol and free fatty acids [22]. ...
... In fact, numerous authors have reported results in terms of fibre reducing glucose release obtained in both soluble and insoluble dietary fibres. In such reports, the authors have explained the effect of fibre in reducing starch degradation on the possibility of fibres coating starch granules and inhibiting enzyme penetration (Brennan et al., 1996;Anderson et al., 1999;Brennan et al., 2002;Brennan, 2005;Granfeldt et al., 2008) and the possibility that the viscous nature of fibres affects the efficiency of enzyme functionality (Jenkins et al., 2002;Flammang et al., 2006;Kendall et al., 2008;Aravind et al., 2012). It is probable that inclusion of DFs to the extruded snack products acts in a viscous-related manner in modulating starch digestion process (Brennan et al., 2012a,b,c). ...
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Cereal products are a main source of carbohydrates in the human diet. Barley and oat grains are considered as functional ingredients that can manipulate postprandial glycemic load while legume material provides high fiber and protein components to food. This research reports on hot extrusion (barrel temperature: 81.9–103.6C, die temperature: 57.3–77.3C and screw speed was around 200 rpm) to develop a barley–oat breakfast cereal which were supplemented with 10% green or yellow pea. The impact of barley–oat ratio and additional pea on physicochemical properties of extruded cereal breakfast was determined. Generally, oat positively affected the hardness of the extrudates, and the hardest extrudates were obtained when the barley–oat ratio was 50:50%. The presence of green and yellow pea increased greenness, redness, chroma and browning index of the samples. The results of in vitro starch digestion test indicated that increase of oat ratio significantly decreased rapidly digested carbohydrates and starch digestibility AUC (area under the curve) (P < 0.05). However, the presence of peas did not significantly affect the starch digestibility AUC value. Practical Applications: The utilization of legume combinations with oat and barley grains can offer a unique balance of carbohydrate and protein composition of ready to eat cereal (RTE) products such as breakfast cereals. It is possible to manipulate the overall glycemic impact of RTEs through the careful utilization of cereal and protein blends. Similarly, the textural characteristics of such products could be manipulated to enhance the crispiness or crunchiness of a product.
... The debranched amylomaltase-treated starches consist of linear malto-oligosaccharides of such DP that they form crystallites by retrogradation. These crystallites are inaccessible to salivary and pancreatic α-amylases, lowering the glycaemic and insulin responses as compared to glucose and soluble fi bers, as Kendall et al. (2008) reported in healthy volunteers. ...
... Other benefits are physiological, including increased levels of shortchain fatty acids such as buyrate, which may reduce the risk of cancer, increase in beneficial gut microflora, control of caloric intake, and lowering of cholesterol and GI (Ferguson, Tasman-Jones, Englyst, & Harris, 2000;Han et al., 2003;Kendall et al., 2008;Liu & Xu, 2008;Lopez et al., 2001;Mahadevamma, Harish Prashanth, & Tharanathan, 2003;Raben et al., 1994;Raigond et al., 2015;Silvi, Rumney, Cresci, & Rowland, 1999;. ...
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No pulse‐based resistant starch (RS) is available commercially although their high amylose content makes them a potentially suitable starch source for making RS. Therefore, to investigate their suitability for the production of RS, starch was isolated from pinto, black, great northern, and lima beans, and characterized to determine proximate composition and pasting properties. Amylose content of bean starches ranged from 30.37 to 33.25% and corn starch 24.20%. Pasting properties of bean starches were generally higher than corn starch. However, corn starch displayed a higher stability. Corn starch also produced a high setback and final viscosity was relative to its amylose content. Bean and corn starches were used to produce retrograded RS (RS3). Resistant starch 3 preparation included a heat–cold method, α‐amylase method, and pullulanase method. Resistant starch 3 produced ranged from 14.86 to 29.67%. Heat–cold method produced a significantly lower percentage RS3 compared to the other two methods. There were no significant differences between the α‐amylase and pullulanase methods. Practical applications The α‐amylase method, a rarely used method for making resistant starch (RS), can produce the same yields of RS3 as the more commonly used pullulanase method. Therefore, food ingredient manufacturers are provided with an alternative effective process to produce RS3 from bean starches in cases where pullulanase is unavailable or otherwise inaccessible.
...  Short chain fatty acids (SCFA), including acetate, butyrate and propionate will be analyzed using standard methods [31,32]. Briefly, the concentrations of SCFA will be measured using a gas chromatography equipped with a flame ionization detector (Hewlett Packard 5890 Series II). ...
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Introduction Data show that disturbances in the gut microbiota play a role in glucose homeostasis, type 1 diabetes (T1D) risk and progression. The prebiotic high amylose maize starch (HAMS) alters the gut microbiome profile and metabolites favorably with an increase in bacteria producing short chain fatty acids (SCFAs) that have significant anti-inflammatory effects. HAMS also improves glycemia, insulin sensitivity and secretion in healthy non-diabetic adults. Additionally, a recent study testing an acetylated and butyrylated form of HAMS (HAMS-AB) that further increases SCFA production prevented T1D in a rodent model without adverse safety effects. The overall objective of this human study will be to assess how daily HAMS-AB consumption impacts the gut microbiome profile, SCFA production, β-cell heath, function and glycemia as well as immune responses in newly-diagnosed T1D youth. Methods and Analysis We hypothesize that HAMS-AB intake will improve the gut microbiome profile, increase SCFA production, improve β-cell health, function and glycemia as well as modulate the immune system. We describe here a pilot, randomized crossover trial of HAMS-AB in 12 newly-diagnosed T1D youth with residual β-cell function. In Aim 1 , we will determine the effect of HAMS-AB on the gut microbiome profile and SCFA production; in Aim 2 , we will determine the effect of HAMS-AB on β-cell health, function and glycemia; and in Aim 3 , we will determine the peripheral blood effect of HAMS-AB on frequency, phenotype and function of specific T cell markers. We anticipate beneficial effects from a simple, inexpensive, and safe dietary approach. Ethics and Dissemination The Institutional Review Board at Indiana University approved the study protocol. The findings of this trial will be submitted to a peer-reviewed pediatric journal. Abstracts will be submitted to relevant national and international conferences. Trial registration number NCT04114357; Pre-results. Article Summary Strengths and limitations of this study The study design (randomized controlled trial, RCT) is the most robust methodology to assess the effectiveness of therapeutic interventions. The findings of this RCT, whether positive or negative, will contribute to the formulation of further recommendations on the use of high amylose maize starch that has been acetylated and butyrylated for improving beta-cell function in children with newly diagnosed type 1 diabetes (T1D).
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This study compared the effects of four types of fiber on satiety and energy intakes at the next meal using a standard double-blinded preload study design. Study participants (14 men and 22 women) each took part in 6 study sessions. Study preloads were a combination of a solid snack and a liquid beverage (energy range 0.78-0.83 MJ) containing four different types of fiber: soluble fiber dextrin (12 g), soluble corn fiber (11.8 g), polydextrose (11.8 g), and resistant starch (11.2g). All four fibers were compared to two control conditions of equal volume: an isoenergetic, low-fiber preload and a lower-energy, low-fiber preload. All preloads were presented twice for a total of 0.35-1.65 MJ and 1-24 g fiber. Satiety ratings were collected for 20 min intervals for 220 min during the morning testing session. A test meal was served at 1200 h and plate waste measured. The five higher-energy preloads led to higher fullness and lower hunger ratings compared to the low-energy control but were not significantly different from each other. Relative to the isoenergetic control, only soluble fiber dextrin significantly suppressed energy intakes (p=0.023). Supplementing beverages with soluble fiber dextrin affects short term energy intake and may have implications for weight control.
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Fibre has been shown to exert a number of benefits on gastrointestinal (GI) health, yet its intake is low. Addition of novel fibres to food products may increase fibre intake and improve gut health. The objective of the present study was to evaluate the influence of three novel fibres on GI outcomes in healthy human subjects. A total of twenty healthy participants (ten men and ten women) with normal BMI (23 (sem 2) kg/m2) participated in the present randomised, double-blind, cross-over study with five treatment periods. Participants consumed a maltodextrin control or 20-25 g/d fibre from soluble maize fibre (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). The treatment periods were 7 d with a 3-week washout between the periods. Stool samples were collected on day 7 of each period, and GI tolerance was assessed via a questionnaire on days 1 and 6. There were no treatment differences in stool weight or consistency. SCF significantly reduced stool pH and increased total SCFA production compared with RS and control. RS+P significantly increased the percentage of butyrate compared with all the other treatments. Overall, GI symptoms were minimal. SCF+P led to the highest GI score on day 1, while RS+P had the highest score on day 6. Both SCF treatments caused a significant shift in the gut microbial community. These functional fibres are generally well tolerated, have minimal effects on laxation and may lead to beneficial changes in SCFA production in healthy adults.
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Fiber is known to be an important part of our nutrition and has many positive health benefits, including weight management and maintaining heart health. In recent years, a number of new ingredients have been manufactured or isolated that are being used to increase the health benefits of a product. Some are used as prebiotics that stimulate the growth of the beneficial bacteria in the gut, or are used as replacements for sugars, starch, or fat in manufactured foods. Fiber supplements have also been produced that can be taken to provide additional fiber to the diet. The term "fiber" does not relate to a single analyte or entity, but instead relates to a multitude of components. This adds to the complexity of analytical testing as there are a number of AOAC International and AACC International official methods which have been validated and can be used. Although methods have been developed for specific fiber ingredients, a number of methods have also been developed to capture just "fiber". These "fiber" methods will capture differing degrees of the different fiber ingredients, so knowledge of the fiber sources is critical. The net result is that a variety of testing approaches may be used, but caution must be exercised in order to ensure that the total fiber result is accurately determined. A critical review of available fiber methodology and possible testing approaches is presented, along with how to accurately interpret and understand results.
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Despite the lack of international agreement regarding the definition and classification of fiber, there is established evidence on the role of dietary fibers in obesity and metabolic syndrome. Beta glucan (β-glucan) is a soluble fiber readily available from oat and barley grains that has been gaining interest due to its multiple functional and bioactive properties. Its beneficial role in insulin resistance, dyslipidemia, hypertension, and obesity is being continuously documented. The fermentability of β-glucans and their ability to form highly viscous solutions in the human gut may constitute the basis of their health benefits. Consequently, the applicability of β-glucan as a food ingredient is being widely considered with the dual purposes of increasing the fiber content of food products and enhancing their health properties. Therefore, this paper explores the role of β-glucans in the prevention and treatment of characteristics of the metabolic syndrome, their underlying mechanisms of action, and their potential in food applications.
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The aim of this study was to determine the effects of three novel fibers on satiety and serum parameters. In a randomized, double-blind, crossover design, fasted subjects (n=20) consumed a low-fiber control breakfast or 1 of 4 breakfasts containing 25 g fiber from soluble corn fiber (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). Visual analog scales assessed appetite and blood samples were collected to measure glucose, insulin, ghrelin and glucagon-like peptide-1 (GLP-1). The fiber treatments did not influence satiety or energy intake compared to control. RS+P significantly reduced glucose, insulin, and GLP-1, but neither SCF treatment differed from control. To conclude, these fibers have little impact on satiety when provided as a mixed meal matched for calories and macronutrients. Additional research regarding the physiological effects of these novel fibers is needed to guide their use as functional ingredients in food products.
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β-glucan is a commonly researched plant cell wall component that when incorporated into food products has been associated with cholesterol and glycaemic response reductions. This study focusses on β-glucan rich fractions from barley and mushroom used in the production of extruded ready to eat snacks. Inclusion of barley β-glucan rich fractions and mushroom β-glucan fractions at 10 % levels increased the total dietary fibre content of extrudates compared to the control (P < 0.05). Product expansion increased with the introduction of both barley and mushroom fraction (P < 0.05) which in turn resulted in a reduction in product hardness (P < 0.05). In vitro digestion protocol illustrated that inclusion of barley and mushroom β-glucan rich fractions manipulated the starch digestibility profile and hence rate of glucose release during digestion compared to the control sample. This in turn resulted in a significant (P < 0.05) reduction in potential glycaemic response of the samples of between 20 and 25 % for barley β-glucan rich fractions and between 17 and 25 % for mushroom β-glucan rich fractions. We conclude that the inclusion of these fractions could be utilised by the food industry to manipulate the glycaemic response of extruded snack products.
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The health-related importance of dietary fibre, as part of a balanced diet, has been recognised for decades. More recently, soluble fibre such as (1→3,1→4)-β-d-glucan (referred to as β-glucan), has been shown to have effects on the glycaemic, insulin, and cholesterol responses to foods. Cereals (such as barley and oats) are good sources for these functional ingredients, with studies clearly demonstrating their potential nutritional benefits. At the same time research has indicated that the efficacy of β-glucans may be related to extraction procedures, and factors such as dose, molecular weight and fine structure, and rheological characteristics of extracted and native β-glucans. Concurrently, research has focussed on the inclusion of β-glucans into both cereal and dairy-based food systems, illustrating their potential as ingredients to manipulate food structure and texture. Thus, β-glucans (from barley, oat, and other cereals) should be regarded as important functional ingredients for the cereal foods industry.
Chapter
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Dietary fiber has long been recommended as part of a healthy diet based on the observations made by Burkitt and Trowell (1975). Since then, epidemiological evidence has consistently shown that populations consuming higher levels of foods containing fiber have decreased risk of a variety of chronic health disorders such as cardiovascular disease, type II diabetes, and certain cancers. Average fiber intake in the United States is approximately 13 g/day for women and 18 g/day for men (National Academy of Sciences, 2006). The FDA recommends a minimum of 20–35 g/day for a healthy adult depending on calorific intake. In many EU countries including France, Germany and the UK (see Figure 9.1 ), fiber intakes are much lower than authorities recommend for men and women (Buttriss and Stokes, 2008; Gray, 2006). Thus, there is a need to increase fiber consumption and many newly isolated or developed fibers can easily be added to beverages and processed foods. The reasons for such low compliance is somewhat complex, however the most basic rationale for not consuming fiber-rich foods is perceived bad taste and mouthfeel and the availability of conventional food items containing fiber.
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Current fiber intakes are alarmingly low, with long-term implications for public health related to risk of coronary heart disease, stroke, hypertension, certain gastrointestinal disorders, obesity, and the continuum of metabolic dysfunctions including prediabetes and type 2 diabetes. Eating patterns high in certain fibers are known to lower LDL cholesterol and blood pressure, lower blood glucose, and decrease insulin resistance in people with prediabetes and type 2 diabetes; help with both weight loss and maintenance; and improve bowel regularity and gastrointestinal health. With >90% of adults and children who fall short of meeting their daily fiber recommendations, the 2010 Dietary Guidelines for Americans once again classified fiber as a nutrient of concern. Despite efforts over the past decade to promote adequate fiber through fruit, vegetable, and whole-grain intakes, fiber consumption has remained flat at approximately half the daily recommended amount. The public health implications of inadequate fiber intake prompted the roundtable session "Filling America's Fiber Gap: Probing Realistic Solutions," which assembled nutrition researchers, educators, and communicators to identify challenges, opportunities, and realistic solutions to help fill the current fiber gap. The roundtable discussions highlighted the need for both consumer and professional education to improve acceptance for and inclusion of grain-based foods with added fiber as one strategy for increasing fiber intakes within daily energy goals.
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With the increase in consumer and processor attention in the functionality of foods, there is a need for a deeper understanding behind how the composition of food affects its nutritional quality. Of particular interest is the role of non-starch polysaccharides and slowly digestible carbohydrates in the possible regulation of starch degradation from carbohydrate rich foods, thus reducing the overall glycaemic impact of such products. The review discusses some of the more recent research findings with regards to food production and nutrition.
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Food intervention is a financially sensible way for prevention and treatment of diabetes. Extruded snack foods are considered high glycaemic products. Our previous research illustrated that postprandial glycaemic responses to snacks are manipulated by altering dietary fibre and starch contents. The current research assessed the effect of psyllium and oat bran on postprandial glycaemia and in vitro digestibility. Addition of psyllium fibre to extruded snack products significantly reduced both the in vitro and in vivo glycaemic responses of products compared to a control snack product recipe. Oat bran inclusion reduced in vitro starch digestibility but not in vivo glycaemic response. The inclusion of oat bran into the snack products appeared to extend the glycaemic response of individuals compared to the control snack, suggesting a possibility of prolonging glucose release and potentially affecting satiety responses. The positive effect in attenuating glucose response means that psyllium fibre could be a target for inclusion by the snack food industry to effectively manipulate postprandial glucose response of individuals.
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Five dietary fibre rich ingredients were used at 5%, 10% and 15% replacement levels in a white flour cereal base to produce an extruded cereal product. The inclusion of the dietary fibres into the flour bases had no significant effect on the expansion ratio of the products. However, the bulk density of the extruded products increased with inulin addition. The pasting properties of the raw flour and fibre base as well as the extruded products were altered with the incorporation of dietary fibre, with guar gum enriched products showing elevated peak and final viscosity readings. This appeared to be related to moisture manipulation and hence the regulation of gelatinisation. In vitro starch hydrolysis of the raw bases and the extruded samples illustrated that the extrusion process significantly increased the availability of carbohydrates for digestion. Additionally, the inclusion of dietary fibres in the raw bases significantly reduced the rate and extent of carbohydrate hydrolysis of the extruded products. As such the addition of dietary fibres to extruded products reduced the amount of readily digestible starch components of breakfast products, and increased the amount of slowly digestible carbohydrates.
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This study investigated the effect of sugar reduction and replacement by corn fibre and polydextrose on yoghurt gel pore size and syneresis. Five yoghurt formulations were produced with 9, 4.5 and 0% sucrose, and also 4.5% with added 2% corn fibre or polydextrose. The increasing demand for sugar reduction in dairy products justifies studies on new formulations such as fibre addition. Sucrose reduction from 9% to 0% led to a decrease in average matrix pore size and increased syneresis. Fibre or polydextrose addition effectively reduced syneresis, despite bigger matrix pore sizes. Fermentation profile, acidity and pH values were not significantly affected by compositional changes.
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Resistant starch (RS) has drawn considerable attention over the last two decades due to its demonstrated and putative positive impacts on health. This has resulted in the development of a variety of analytical protocols for its determination, hence a comprehensive review of methodologies for analyzing resistant starch is warranted. Adding to the complexity, the RS contents of starchy materials vary widely and RS levels are impacted by processing. This review compares commonly used methods for the determination of RS, briefly reviews the process of starch digestion in the human, and discusses the complications and challenges associated with determining RS in foods.
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The objective of the present study was to determine the maximum dose of resistant maltodextrin (Fibersol(®)-2, a non-viscous water-soluble dietary fiber), that does not induce transitory diarrhea. Ten healthy adult subjects (5 men and 5 women) ingested Fibersol(®)-2 at increasing dose levels of 0.7, 0.8, 0.9, 1.0, and 1.1 g/kg body weight (bw). Each administration was separated from the previous dose by an interval of 1 wk. The highest dose level that did not cause diarrhea in any subject was regarded as the maximum non-effective level for a single dose. The results showed that no subject of either sex experienced diarrhea at dose levels of 0.7, 0.8, 0.9, or 1.0 g/kg bw. At the highest dose level of 1.1 g/kg bw, no female subject experienced diarrhea, whereas 1 male subject developed diarrhea with muddy stools 2 h after ingestion of the test substance. Consequently, the maximum non-effective level for a single dose of the resistant maltodextrin Fibersol(®)-2 is 1.0 g/kg bw for men and >1.1 g/kg bw for women. Gastrointestinal symptoms were gurgling sounds in 4 subjects (7 events) and flatus in 5 subjects (9 events), although no association with dose level was observed. These symptoms were mild and transient and resolved without treatment.
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In the past few years research in the nanotechnology field has increased, especially in the pharmaceutical industry. But, in the recent decades, application of nanotechnology in the food industry has become a reality due to its advantages as vectors for bioactive compounds, assuring health benefits. In fact, nanotechnology has been developed and adapted in the food industry for improvement of food processing and preservation. Therefore, the aim of this work was to produce stable solid lipid nanoparticles (SLNs), loaded with rosmarinic acid (RA, polyphenol with antioxidant capacity), using as lipid matrices Witepsol H15 and Carnauba wax, for posterior incorporation in food matrices. In order to accomplish the objectives, different SLNs were developed according to a factorial design and several properties (particle size, polydispersity index, zeta potential and the percentage efficiency of compound association was calculated) were characterized in order to evaluate their potential and stability. It was shown that the most stable formulations were those produced with 0.5% (w/v) of lipid combined with 1 – 2% (v/v) of surfactant, which were selected for further studies. Thermal and morphological properties were also studied, through differential scanning calorimetry and scanning electron microscopy, respectively. The RA-SLNs, in general, presented melting temperatures lower than the controls (lipids and SLNs without RA). Morphological analysis showed spherical shape for Witepsol RA-SLNs, whereas Carnauba wax RA-SLNs presented cylindrical shape. By FTIR analysis, it was possible to confirm the encapsulation of RA by Witepsol and Carnauba wax. The passage of RA-SLNs through gastrointestinal tract simulated conditions was subsequently tested and it was possible to confirm the release of RA during the intestinal phase. The percentage of release was higher in the long digestion (ca. 120 min) and the RA exhibited antioxidant capacity when released in the intestine, proving its stability throughout the gastrointestinal tract. Finally, in order to study the stability of the RA-SLNs when added to a food matrix, they were incorporated in yogurt. Product and SLNs stability throughout 28 days of storage were confirmed, and lactic acid bacteria of starter culture were not affected. As conclusion, it was possible to develop SLNs with both lipids, which demonstrated high stability throughout storage, assuring these SLNs to be a good vehicle for RA.
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This chapter describes the various compounds that can act as prebiotic fibers: their structure, occurrence, production, and physiological effects (health effects) will be presented. The basis for the description is the latest definitions for dietary fibers and for prebiotics. Using as much as possible data from human studies, both the fiber and the prebiotic properties will be described of a variety of compounds. Based on the presented data the latest developments in the area of prebiotics, fibers and gut and immune health will be discussed in more detail as they show best what the potential impact of prebiotics on health of the human host might be. © 2015 Elsevier Inc. All rights reserved.
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The rising prevalence of obesity and the vulnerability of the pediatric age group have highlighted the critical need for a careful consideration of effective, safe, remedial and preventive dietary interventions. Amylose starch (RS2) from high-amylose maize (HAM) ferments in the gut and affects body weight. One hundred and ten children, of 7-8 (n=91) or 13-14 (n=19) years of age scored the sensory qualities of a yogurt supplemented with either HAM-RS2 or an amylopectin starch. The amylopectin starch yogurt was preferred to the HAM-RS2-enriched yogurt by 7-8 year old panelists ( P<0.0001). Appearance, taste, and sandiness scores given by 13- to 14-year-old panelists were more favorable for the amylopectin starch yogurt than for HAM-RS2-enriched yogurt ( P<0.05). HAM-RS2 supplementation resulted in acceptable (≥6 on a 1-9 scale) sensory and hedonic ratings of the yogurt in 74% of subjects. Four children consumed a HAM-RS2-enriched yogurt for four weeks to test its fermentability in a clinical trial. Three adolescents, but not the single pre-pubertal child, had reduced stool pH ( P=0.1) and increased stool short-chain fatty acids (SCFAs) ( P<0.05) including increased fecal acetate ( P=0.02), and butyrate ( P=0.089) from resistant starch (RS) fermentation and isobutyrate ( P=0.01) from protein fermentation post-treatment suggesting a favorable change to the gut microbiota. HAM-RS2 was not modified by pasteurization of the yogurt, and may be a palatable way to increase fiber intake and stimulate colonic fermentation in adolescents. Future studies are planned to determine the concentration of HAM-RS2 that offers the optimal safe and effective strategy to prevent excessive fat gain in children.
Chapter
Carbohydrates (CHO) provide a large percentage of our daily energy and are consumed in a wide variety of forms. Under isoenergetic conditions there is evidence of a macronutrient hierarchy for satiety (protein > CHO > fat), energy density (ED) plays a major role, but the causal relationships and underpinning mechanisms of the macronutrients are still being elicited. Effects of CHOs on food intake are greatly complicated by the wide variety of forms in which CHO is consumed. Numerous theories have been proposed as to the effect of CHO on satiety, with conflicting recommendations made both for increase and decrease in our daily diet, and these are discussed in this chapter. Hypotheses include effects on circulation and storage CHOs, including Mayer's original glucostatic theory of low circulating blood glucose and Flatt's glycogenostatic theory of low glycogen stores in liver and muscle both triggering hunger, and the glycaemic index (GI) theory of 'fast release' available CHO causing rapid high spikes and rebound low troughs in blood glucose to also stimulate hunger. Conversely, there are the peptide theory of CHO-driven secretion of circulating satiety biomarkers and/or peptides, and the high-fibre theory wherein foods with a high fibre content and/or a low GI and/or enhanced large bowel microbiota suppress hunger. In addition, low ED theory supports complex/fibrous CHO/low energy foods for suppression of hunger, whilst the low CHO theory, wherein total CHO intake is restricted, predicts suppression of both GI and hunger.
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The digestibility and estimated glycemic indices (GI) of native (NWS), cross-linked (CLWS) and hydroxypropylated wheat starches (HPWS) were obtained by in vitro enzymatic hydrolysis. The resistant starch (RS) content and GI were found to be 6.59 and 93.13 for NWS, 7.57 and 92.20 for CLWS, and also 13.15 and 89.04 for HPWS, respectively. The amounts of glucose release for CLWS were approximately 6-11%, and for HPWS were 16-19% lower than that for NWS after digestion at simulated intestinal condition (SIC). The linear and two-term exponential models were fitted well to the experimental glucose release data at simulated gastric condition (SGC) and SIC, respectively (R2 = 0.858-0.991). After digestion at SIC, the consistency coefficient (k) values drastically decreased (73.02-90.27%), while the flow behavior index (n) increased (155.56-363.64%). Therefore, the amounts of glucose release can be controlled by manipulating the structure of native starches using chemical modifications such as cross-linking and hydroxypropylation.
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Andean roots and tubers are underexploited crops; many contain compounds beneficial to health so, a greater knowledge of their properties is important to encourage their consumption. The aim of this work was to study the content of bioactive compounds of yacon and oca and their effect on intestinal health using as model rats of the Wistar strain. Two varieties of ocas (Overa and Rosada) and yacon, which contain significant amounts of fructooligosaccharides and phenolic compounds, were chosen. Rats Wistar strains were fed during two months with diets containing these foods in amounts sufficient to provide 8% of fiber. A significant decrease in pH values and an increment in lactobacilli and bifidobacteria counts in the cecum of rats fed with inulin, Oca Rosada and Overa was observed; there was no significant decrease in enterobacteriaceae and enterococci counts. The cecum antioxidant activity was incremented in rats fed with the experimental foods with respect to the control diets. The components of dietary fiber and phenolic compounds content in yacon and oca produce effects that contribute to the intestinal health of the experimental animals.
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New starch preparations were produced by thermolysis of potato starch acidified with hydrochloric and citric acids in a microwave oven. Effect of microwave heating with different exposure times and various radiation level on physical, chemical properties and total dietary fibre (TDF) content in starch preparations was studied. Physicochemical characteristics of dextrins including water solubility, water binding capacity, acidity, dextrose equivalent, intrinsic viscosity, HPSEC chromatograms were done. TDF content was determined by AOAC Official Method 991.43. Moreover, the stability of dextrins in in vitro model simulating the stomach and small intestine was tested. Studies showed that starch dextrins were characterized by increased dietary fibre content and increased resistance to digestion and absorption in the upper part of digestive tract.
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Soluble dietary fibre (DF), including β-glucan, guar gum, psyllium and alginate, reduce the absorption rate of glucose after the consumption of a high carbohydrate load through its beneficial viscosity properties. The addition of DF to high carbohydrate liquids and foods has shown significant reductions in postprandial glucose absorption albeit palatability issues at the concentrations required to see the beneficial effect have limited their applications as a functional food ingredient. Changes in the physiochemical properties of the DFs following food processing negatively impacts on DF viscosity and ultimately reduces efficacy. Research is focusing on exploring processing procedures that minimize disruption to these physicochemical properties such as changes to temperature , molecular weight and contact times. Furthermore, the development of novel composite DF blends that draw on individual characteristics is a novel method of utilizing DF as a functional food ingredient for its glycemic lowering ability.
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In this research, corn resistant starch (CRS) was mixed with four kinds of soluble dietary fibers (chitosan, flaxseed gum, xanthan gum, and konjac gum). The pasting and rheological properties, microstructure, and X-ray diffraction spectrum of the mixed system were investigated by rapid viscosity analyzer (RVA), rheometer, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). The pasting curves showed that the addition of chitosan could reduce the viscosity of CRS paste, while the flaxseed gum, xanthan gum and konjac gum increased the viscosity. All complex systems had shear thinning properties in the rheological steady flow experiments. Soluble dietary fibers significantly increased the value of viscosity coefficient (K) of the CRS, however, the value of flow characteristic index (n) was decreased with increasing concentration of soluble dietary fibers. Soluble dietary fibers addition resulted in higher storage modulus and loss modulus (G′ and G″) of CRS paste, as well as giving rise to high viscoelasticity. SEM confirmed that the addition of soluble dietary fibers made the starch granules more easily aggregated in the mixed systems. X-ray diffraction spectrum analysis showed that the addition of soluble dietary fibers did not change the B and V type crystalline pattern of CRS, and both the concentrations and types of soluble dietary fibers had significant effects on the crystallinity of mixed systems. This study reported four mixtures with CRS and provided useful information for functional food.
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Objective Determining the available energy (caloric value) of dietary non-digestible fibers that are fermented to varying degrees by intestinal microbes and metabolized to short chain fatty acids is important for provision of accurate information to food and beverage manufacturers for reformulation and labeling purposes. The objective of this human study was to determine the available energy of soluble fiber products by measuring post consumption breath hydrogen, with inulin as a control. Methods PROMITOR® Soluble Corn Fiber 70 (SCF70) and PROMITOR® Soluble Corn Fiber 85B (SCF85B) are Tate & Lyle dietary fiber products with 70% and 85% fiber, respectively. The fiber portion of these products is structurally representative of the fiber portion of all PROMITOR® SCF products. The study conducted was a randomized, double-blind, crossover design. Breath hydrogen was quantified following consumption of beverages consisting of 8 oz. of water and: inulin (control), SCF70, or SCF85B at 5, 10, or 15 g (total ingredient weight, “as is”). Subjects were generally healthy men and women (N = 19), age 18 to 34 years, with body mass index (BMI) 19.3 to 24.8 kg/m². The primary outcome was incremental area under the curve over 10 h (iAUC0–10 h) for inulin, SCF70, and SCF85B at each dose. The available energy (kcal/g ingredient and kcal/g fiber) from SCF70 and SCF85B at each dose was then calculated using inulin as the reference. Results Results demonstrated that breath hydrogen production was significantly lower following consumption of SCF70 and SCF85B compared to inulin at all consumption amounts. There were no significant differences in breath hydrogen production following consumption of SCF70 compared to SCF85B. Conclusion The available energy per gram of fiber was not significantly different between the SCF70 and SCF85B PROMITOR® products. The available energy of the fiber portion of PROMITOR® SCF products was determined to be 0.2 kcal/gram.
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The effects of different concentrations of xanthan and konjac gums on the pasting, rheological properties, microstructure, crystallinity, and digestibility of mung bean resistant starch (MRS) were investigated. Based on the results of pasting properties, the adjunction of gums increased the peak, breakdown, and final viscosities of resistant starch. Compared with resistant starch, the addition of gum significantly increased the K value and dynamic moduli (G', G“) of MRS with increasing gum concentration. This finding indicates that the mixtures had higher viscoelasticity. Mixtures with xanthan gum of MRS had larger starch particle compared with MRS, as revealed by SEM. All starches showed B and V-type crystallinity with high crystallinity. MRS had the highest summation of resistant starch (RS) and slowly digestible starch (SDS) of 71.89%. MRS had the lowest hydrolysis rate, which obviously decreased from 71.89% to 57.71% with increasing konjac gum from 0 to 0.30%.
Article
The objective of this research was to measure in vitro hydrolytic digestion characteristics, glycemic and insulinemic responses, and true metabolizable energy (TME(n)) content of select soluble fiber dextrins (SFDs) and pullulans. The SFDs were derived either from tapioca starch or from corn starch. The pullulans were of low, intermediate, and high molecular weight. Soluble fiber dextrins varied in digestibility, with all substrates resulting in low to intermediate in vitro monosaccharide digestion. Pullulans were nearly completely hydrolyzed after simulated hydrolytic digestion. The glycemic response with dogs varied widely among SFDs, with all but one SFD substrate having lower glycemic response than maltodextrin (Malt). The pullulans all resulted in low glycemic values. Lower relative insulinemic responses (RIR) compared to the Malt control were noted for all SFDs and pullulans. True metabolizable energy (TME(n)) values for SFDs obtained using roosters were lower than for Malt, with tapioca-based SFDs having numerically higher values than corn-based SFDs. Pullulans resulted in higher TME(n) values than did SFDs. Soluble fiber dextrins and pullulans may be suitable candidates for reduced calorie and glycemic foodstuffs.
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Clinical trials using antihyperglycemic medications to improve glycemic control have not demonstrated the anticipated cardiovascular benefits. Low-glycemic index diets may improve both glycemic control and cardiovascular risk factors for patients with type 2 diabetes but debate over their effectiveness continues due to trial limitations. To test the effects of low-glycemic index diets on glycemic control and cardiovascular risk factors in patients with type 2 diabetes. A randomized, parallel study design at a Canadian university hospital research center of 210 participants with type 2 diabetes treated with antihyperglycemic medications who were recruited by newspaper advertisement and randomly assigned to receive 1 of 2 diet treatments each for 6 months between September 16, 2004, and May 22, 2007. High-cereal fiber or low-glycemic index dietary advice. Absolute change in glycated hemoglobin A(1c) (HbA(1c)), with fasting blood glucose and cardiovascular disease risk factors as secondary measures. In the intention-to-treat analysis, HbA(1c) decreased by -0.18% absolute HbA(1c) units (95% confidence interval [CI], -0.29% to -0.07%) in the high-cereal fiber diet compared with -0.50% absolute HbA(1c) units (95% CI, -0.61% to -0.39%) in the low-glycemic index diet (P < .001). There was also an increase of high-density lipoprotein cholesterol in the low-glycemic index diet by 1.7 mg/dL (95% CI, 0.8-2.6 mg/dL) compared with a decrease of high-density lipoprotein cholesterol by -0.2 mg/dL (95% CI, -0.9 to 0.5 mg/dL) in the high-cereal fiber diet (P = .005). The reduction in dietary glycemic index related positively to the reduction in HbA(1c) concentration (r = 0.35, P < .001) and negatively to the increase in high-density lipoprotein cholesterol (r = -0.19, P = .009). In patients with type 2 diabetes, 6-month treatment with a low-glycemic index diet resulted in moderately lower HbA(1c) levels compared with a high-cereal fiber diet. Trial Registration clinicaltrials.gov identifier: NCT00438698.
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To define the type of dietary fibre of fibre analogue with the greatest potential use in diabetic treatment, groups of four to six volunteers underwent 50-g glucose tolerance tests (GTT) with and without the addition of either guar, pectin, gum tragacanth, methylcellulose, wheat bran, or cholestyramine equivalent to 12 g fibre. The addition of each substance significantly reduced blood glucose concentration at one or more points during the GTT and generally reduced serum insulin concentrations. The greatest flattening of the glucose response was seen with guar, but this effect was abolished when hydrolysed non-viscous guar was used. The reduction in the mean peak rise in blood glucose concentration for each substance correlated positively with its viscosity (r = 0.926; P less than 0.01), as did delay in mouth-to-caecum transit time (r = 0.885; P less than 0.02). Viscous types of dietary fibre are therefore most likely to be therapeutically useful in modifying postprandial hyperglycaemia.
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For nutritional purposes, starch in foods may be classified into rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). RS may be further divided into three categories according to the reason for resistance to digestion. A method is reported for the measurement of total starch, RDS, SDS, RS and three RS fractions in starchy foods, using controlled enzymic hydrolysis with pancreatin and amyloglucosidase. The released glucose is measured by colorimetry, using a glucose oxidase kit. Values for RDS and SDS in foods obtained by the method reflect the rate of starch digestion in vivo. Values for RS are similar to the amounts of starch escaping digestion in the small intestine of ileostomates, and are a guide to the amounts of starch likely to enter the colon for fermentation. Results are given for a number of starchy foods.
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A new method for measuring the rate of in-vitro starch digestion in products with a structure 'as eaten' is introduced. An equivalent amount of potentially available starch from each product was chewed by subjects, expectorated into a beaker and incubated with pepsin. The incubate was thereafter transferred to a dialysis tubing and incubated with pancreatic alpha-amylase for 3 h. Samples were removed from the dialysate at time intervals and the degree of hydrolysis was calculated as the proportion of the potentially available starch degraded to maltose. A hydrolysis index (HI) was calculated as the area under the hydrolysis curve with the product as a percentage of the corresponding area with white wheat bread. The method was applied to 21 cereal and legume products, chosen to cover as wide a range as possible with respect to metabolic response, and to include several of the proposed mechanisms to differences in metabolic behaviour of starch. The accuracy of the in-vitro method was evaluated versus the metabolic responses obtained with the same products in healthy subjects. A significant correlation between HI and glycaemic index (GI) was obtained in cereal as well as in legume products. A significant correlation was also obtained between HI and insulin index (II) with pooled data from all products. However, in the case of II no correlation was obtained with the legume products only. It is concluded that the presently described in-vitro procedure offers a good potential to predict the metabolic behaviour of starchy foods.
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Intake of carbohydrates that provide a large glycemic response has been hypothesized to increase the risk of NIDDM, whereas dietary fiber is suspected to reduce incidence. These hypotheses have not been evaluated prospectively. We examined the relationship between diet and risk of NIDDM in a cohort of 42,759 men without NIDDM or cardiovascular disease, who were 40-75 years of age in 1986. Diet was assessed at baseline by a validated semiquantitative food frequency questionnaire. During 6-years of follow-up, 523 incident cases of NIDDM were documented. The dietary glycemic index (an indicator of carbohydrate's ability to raise blood glucose levels) was positively associated with risk of NIDDM after adjustment for age, BMI, smoking, physical activity, family history of diabetes, alcohol consumption, cereal fiber, and total energy intake. Comparing the highest and lowest quintiles, the relative risk (RR) of NIDDM was 1.37 (95% CI, 1.02-1.83, P trend = 0.03). Cereal fiber was inversely associated with risk of NIDDM (RR = 0.70; 95% CI, 0.51-0.96, P trend = 0.007; for > 8.1 g/day vs. < 3.2 g/day). The combination of a high glycemic load and a low cereal fiber intake further increased the risk of NIDDM (RR = 2.17, 95% CI, 1.04-4.54) when compared with a low glycemic load and high cereal fiber intake. These findings support the hypothesis that diets with a high glycemic load and a low cereal fiber content increase risk of NIDDM in men. Further, they suggest that grains should be consumed in a minimally refined form to reduce the incidence of NIDDM.
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Little is known about the effects of the amount and type of carbohydrates on risk of coronary heart disease (CHD). The objective of this study was to prospectively evaluate the relations of the amount and type of carbohydrates with risk of CHD. A cohort of 75521 women aged 38-63 y with no previous diagnosis of diabetes mellitus, myocardial infarction, angina, stroke, or other cardiovascular diseases in 1984 was followed for 10 y. Each participant's dietary glycemic load was calculated as a function of glycemic index, carbohydrate content, and frequency of intake of individual foods reported on a validated food-frequency questionnaire at baseline. All dietary variables were updated in 1986 and 1990. During 10 y of follow-up (729472 person-years), 761 cases of CHD (208 fatal and 553 nonfatal) were documented. Dietary glycemic load was directly associated with risk of CHD after adjustment for age, smoking status, total energy intake, and other coronary disease risk factors. The relative risks from the lowest to highest quintiles of glycemic load were 1.00, 1.01, 1. 25, 1.51, and 1.98 (95% CI: 1.41, 2.77 for the highest quintile; P for trend < 0.0001). Carbohydrate classified by glycemic index, as opposed to its traditional classification as either simple or complex, was a better predictor of CHD risk. The association between dietary glycemic load and CHD risk was most evident among women with body weights above average ¿ie, body mass index (in kg/m(2)) >/= 23. These epidemiologic data suggest that a high dietary glycemic load from refined carbohydrates increases the risk of CHD, independent of known coronary disease risk factors.
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The use of diets with low glycemic index (GI) in the management of diabetes is controversial, with contrasting recommendations around the world. We performed a meta-analysis of randomized controlled trials to determine whether low-GI diets, compared with conventional or high-GI diets, improved overall glycemic control in individuals with diabetes, as assessed by reduced HbA(1c) or fructosamine levels. Literature searches identified 14 studies, comprising 356 subjects, that met strict inclusion criteria. All were randomized crossover or parallel experimental design of 12 days' to 12 months' duration (mean 10 weeks) with modification of at least two meals per day. Only 10 studies documented differences in postprandial glycemia on the two types of diet. Low-GI diets reduced HbA(1c) by 0.43% points (CI 0.72-0.13) over and above that produced by high-GI diets. Taking both HbA(1c) and fructosamine data together and adjusting for baseline differences, glycated proteins were reduced 7.4% (8.8-6.0) more on the low-GI diet than on the high-GI diet. This result was stable and changed little if the data were unadjusted for baseline levels or excluded studies of short duration. Systematically taking out each study from the meta-analysis did not change the CIs. Choosing low-GI foods in place of conventional or high-GI foods has a small but clinically useful effect on medium-term glycemic control in patients with diabetes. The incremental benefit is similar to that offered by pharmacological agents that also target postprandial hyperglycemia.
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Increasing evidence suggests an important role of carbohydrate quality in the development of type 2 diabetes. Our objective was to prospectively examine the association between glycemic index, glycemic load, and dietary fiber and the risk of type 2 diabetes in a large cohort of young women. In 1991, 91249 women completed a semiquantitative food-frequency questionnaire that assessed dietary intake. The women were followed for 8 y for the development of incident type 2 diabetes, and dietary information was updated in 1995. We identified 741 incident cases of confirmed type 2 diabetes during 8 y (716 300 person-years) of follow-up. After adjustment for age, body mass index, family history of diabetes, and other potential confounders, glycemic index was significantly associated with an increased risk of diabetes (multivariate relative risks for quintiles 1-5, respectively: 1, 1.15, 1.07, 1.27, and 1.59; 95% CI: 1.21, 2.10; P for trend = 0.001). Conversely, cereal fiber intake was associated with a decreased risk of diabetes (multivariate relative risks for quintiles 1-5, respectively: 1, 0.85, 0.87, 0.82, and 0.64; 95% CI: 0.48, 0.86; P for trend = 0.004). Glycemic load was not significantly associated with risk in the overall cohort (multivariate relative risks for quintiles 1-5, respectively: 1, 1.31, 1.20, 1.14, and 1.33; 95% CI: 0.92, 1.91; P for trend = 0.21). A diet high in rapidly absorbed carbohydrates and low in cereal fiber is associated with an increased risk of type 2 diabetes.
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Regulation of blood glucose to achieve near-normal levels is a primary goal in the management of diabetes, and, thus, dietary techniques that limit hyperglycemia following a meal are likely important in limiting the complications of diabetes. Low-carbohydrate diets are not recommended in the management of diabetes. Although dietary carbohydrate is the major contributor to postprandial glucose concentration, it is an important source of energy, water-soluble vitamins and minerals, and fiber. Thus, in agreement with the National Academy of Sciences-Food and Nutrition Board, a recommended range of carbohydrate intake is 45-65% of total calories. In addition, because the brain and central nervous system have an absolute requirement for glucose as an energy source, restricting total carbohydrate to < 130 g/day is not recommended. Both the amount (grams) of carbohydrate as well as the type of carbohydrate in a food influence blood glucose level. The total amount of carbohydrate consumed is a strong predictor of glycemic response, and, thus, monitoring total grams of carbohydrate, whether by use of exchanges or carbohydrate counting, remains a key strategy in achieving glycemic control. A recent analysis of the randomized controlled trials that have examined the efficacy of the glycemic index on overall blood glucose control indicates that the use of this technique can provide an additional benefit over that observed when total carbohydrate is considered alone. Although this statement has focused primarily on the role of carbohydrate in the diet, the importance of achieving/ maintaining a healthy body weight (particularly in type 2 diabetes) in the management of diabetes should not be ignored. Moderate weight loss in overweight/obese individuals with type 2 diabetes results in improved control of hyperglycemia as well as in a reduction in risk factors for cardiovascular disease. Because much of the risk of developing type 2 diabetes is attributable to obesity, maintenance of a healthy body weight is strongly recommended as a means of preventing this disease. The relationship between glycemic index and glycemic load and the development of type 2 diabetes remains unclear at this time.
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The objective of this article was to assess mortality risks at different levels of fasting blood glucose (FBG) in Taiwan, with particular attention to those pre-diabetic subjects with impaired fasting glucose (IFG). Governmental employees and schoolteachers were followed up for an average of 11 years. With the use of Cox regression analyses, mortality risks were calculated for 36,386 subjects, aged 40-69. FBG > or =110 mg/dl was associated with increased mortality risks for all causes, cardiovascular diseases (CVD), and diabetes. IFG, when defined as 110-125 mg/dl, was associated with a significant increase for CVD and/or diabetes mortality. These mortality risks remained elevated when known CVD risk factors were adjusted for. The IFG group shared risk factor characteristics more with the FBG > or =126 mg/dl group than with the FBG <110 mg/dl group. When IFG was defined as 100-125 mg/dl, the number of subjects quadrupled, but mortality risks diminished substantially because of the inclusion of 100-109 mg/dl group. The lowest FBG group, 50-75 mg/dl, had a significant 2-fold risk from all causes. There was an overall J-shaped relationship between all-cause mortality and FBG. IFG, when defined as 110-125 mg/dl, is an independent risk factor and should be aggressively treated as a disease because its subsequent mortality risks for CVD and diabetes were significantly increased. The newly defined IFG at 100-125 mg/dl did not have the predictive power for later increases in CVD or diabetes mortality.
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Among the various classes of processed starchy foods, wheat-based cereal products exhibit a wide range in glycemic and insulinemic responses. Understanding starch behavior during cooking and processing may help identify strategies that lower postprandial glycemia and insulinemia. To determine the relationship between the in vivo glycemic index (GI)/insulinemic index (II) and in vitro digestibility and composition characteristics (rapidly available glucose and slowly available glucose, RAG and SAG respectively) of 24 plain sweet biscuits (cookies). The products were commercially available and selected on the basis of their high starch content. In vivo responses (GI and II) were measured by standardised methods over 7 studies, with 12 subjects in each study (30 males, 42 females). In vitro digestibility characteristics were measured by the Englyst procedure. The observed GI ranged from 38 to 60 (low to moderate) with the majority between 40 and 50, and correlated strongly with the observed insulinemic index (r = 0.76, P < 0.0001). The digestibility profile of carbohydrates was significantly correlated to in vivo responses (SAG and GI: r = -0.41; p = 0.04; SAG and II: r = -0.52; p < 0.01; RAG and GI: r = 0.5; p = 0.01; RAG and II: r = 0.34; p = 0.1) and explained in vivo responses better than fat, protein and fiber content amongst this selection of plain sweet biscuits. The findings indicate that plain sweet biscuits have a low GI and a moderate II and that these characteristics are correlated to in vitro starch digestibility and are dependent on the type of processing.
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To optimize identification of future diabetic patients, the American Diabetes Association (ADA) introduced criteria for impaired fasting glucose (IFG) in 1997 (IFG 6.1 mmol/l [IFG6.1]) and lowered the threshold from 6.1 to 5.6 mmol/l (IFG5.6) in 2003. Our aim was to assess the consequences of lowering the IFG cutoff on the risk of cardiovascular disease (CVD) mortality and to evaluate whether this risk is explained by a conversion to type 2 diabetes within 6.4 years. In a population-based cohort, the Hoorn Study, plasma glucose was determined in 1989 and 1996 (n = 1,428). Subjects were classified in 1989 according to 1997 and 2003 ADA criteria. Subjects with IFG in 1989 were further classified according to diabetes status in 1996. Hazard ratios for CVD mortality (n = 81) in the period 1996-2005 were adjusted for age and sex. Subjects with IFG6.1, but not IFG5.6, had a significantly higher CVD mortality risk than normal fasting glucose (NFG) subjects. Subjects who converted from IFG to diabetes (IFG6.1: 42%; IFG5.6: 21%) had a more than twofold risk of CVD mortality (IFG6.1: 2.47 [1.17-5.19]; IFG5.6: 2.14 [1.12-4.10]) than subjects with NFG. IFG subjects who did not develop diabetes did not have significantly higher CVD mortality risks (IFG6.1: 1.50 [0.72-3.15]; IFG5.6: 1.15 [0.69-1.93]). The lower cutoff for IFG (ADA 2003 criteria) results in a category of IFG that no longer represents a high-risk state of CVD. Furthermore, only subjects who convert from IFG to diabetes have a high risk of CVD mortality.
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The metabolic syndrome (MetS) is defined as a clustering of cardiovascular risk factors characterized by insulin resistance. We investigated the relationship of the MetS and its single components, defined by all six different criteria, with coronary heart disease (CHD), cardiovascular disease (CVD), and all-cause mortality in a prospective population-based study. The MetS was defined according to the World Health Organization (WHO), the European Group for the Study of Insulin Resistance (EGIR), the National Cholesterol Education Program (NCEP), the American College of Endocrinology (ACE), the International Diabetes Federation (IDF), and the American Heart Association (updated NCEP) criteria. We investgated the relationship of the MetS defined by aforementioned six criteria with CHD, CVD, and all-cause mortality with Cox regression analyses in a non-diabetic Finnish population of 1025 subjects, aged 65-74 years, during the 13-year follow-up. The MetS defined by all aforementioned criteria was associated with a statistically significant risk for CVD mortality when adjusted for all confounding variables (Hazards Ratios, HRs from 1.31 to 1.51). The MetS defined by the WHO, ACE, and IDF criteria was associated with an increased risk of CHD mortality (HRs from 1.42 to 1.58). There was no association between the MetS by any criteria and all-cause mortality. Of the single components of the MetS, the following predicted CVD mortality in multivariable models: impaired fasting glucose by the WHO, NCEP, and ACE criteria (HR 1.34) and by the IDF and updated NCEP criteria (HR 1.29); impaired glucose tolerance by the WHO and ACE criteria (HR 1.55); low HDL cholesterol by the EGIR criteria (HR 1.50) and by the NCEP, IDF, and updated NCEP criteria (HR 1.29); and microalbuminuria according to the WHO definition (HR 1.86). The MetS defined by all six current criteria predicts CVD mortality in elderly subjects. However, of the single components of the MetS, IFG, IGT, low HDL cholesterol, and microalbuminuria predicted CVD mortality with equal or higher HRs when compared with the different definitions of the MetS. Therefore, our study suggests that the MetS is a marker of CVD risk, but not above and beyond the risk associated with its individual components.
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Inconsistent findings from observational studies have prolonged the controversy over the effects of dietary glycemic index (GI) and glycemic load (GL) on the risk of certain chronic diseases. The objective was to evaluate the association between GI, GL, and chronic disease risk with the use of meta-analysis techniques. A systematic review of published reports identified a total of 37 prospective cohort studies of GI and GL and chronic disease risk. Studies were stratified further according to the validity of the tools used to assess dietary intake. Rate ratios (RRs) were estimated in a Cox proportional hazards model and combined by using a random-effects model. From 4 to 20 y of follow-up across studies, a total of 40 129 incident cases were identified. For the comparison between the highest and lowest quantiles of GI and GL, significant positive associations were found in fully adjusted models of validated studies for type 2 diabetes (GI RR = 1.40, 95% CI: 1.23, 1.59; GL RR = 1.27, 95% CI: 1.12, 1.45), coronary heart disease (GI RR = 1.25, 95% CI: 1.00, 1.56), gallbladder disease (GI RR = 1.26, 95% CI: 1.13, 1.40; GL RR = 1.41, 95% CI: 1.25, 1.60), breast cancer (GI RR = 1.08, 95% CI: 1.02, 1.16), and all diseases combined (GI RR = 1.14, 95% CI: 1.09, 1.19; GL RR = 1.09, 95% CI: 1.04, 1.15). Low-GI and/or low-GL diets are independently associated with a reduced risk of certain chronic diseases. In diabetes and heart disease, the protection is comparable with that seen for whole grain and high fiber intakes. The findings support the hypothesis that higher postprandial glycemia is a universal mechanism for disease progression.
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The glycaemic index (GI) is a measure of the ability of a food to raise blood sugar. Written by one of the co-inventors of the term, this is a clear and balanced review of current knowledge on this controversial concept. The book explores all the key issues of the definition of the GI, how to measure the GI of a food, how to apply GI information to meals and diets, the reasons why foods have different GI values and the impact of altering a diet GI on health and disease. The book highlights the benefits and the problems surrounding the GI concept, whilst encouraging readers to think critically about the issues involved.
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Moong bean (Phaseolus aureus), faba bean (Faba vulgaris), and field bean (Dolichos lablab) were tested for in vitro and in vivo glycemic effects. An in vitro technique was used that measured the rate and extent of starch digestion to predict the glycemic response. The in vivo response was determined by studying the glycemic index (GI) of legumes in non-insulin dependent diabetic (NIDD) subjects. The in vitro rate of starch hydrolysis was least with faba bean and maximum with moong bean. The average GI values were 30.6 ± 2.28 for faba bean, 31.6±3.15 for field bean and 54.6±3.54 for moong bean. By their low post-prandial glucose response and low starch digestibility rates, faba bean and field bean would be ideal for inclusion in the diets of diabetics.
Article
Objective. —To examine prospectively the relationship between glycemic diets, low fiber intake, and risk of non—insulin-dependent diabetes mellitus.Desing. —Cohort study.Setting. —In 1986, a total of 65173 US women 40 to 65 years of age and free from diagnosed cardiovascular disease, cancer, and diabetes completed a detailed dietary questionnaire from which we calculated usual intake of total and specific sources of dietary fiber, dietary glycemic index, and glycemic load.Main Outcome Measure. —Non—insulin-dependent diabetes mellitus.Results. —During 6 years of follow-up, 915 incident cases of diabetes were documented. The dietary glycemic index was positively associated with risk of diabetes after adjustment for age, body mass index, smoking, physical activity, family history of diabetes, alcohol and cereal fiber intake, and total energy intake. Comparing the highest with the lowest quintile, the relative risk (RR) of diabetes was 1.37 (95% confidence interval [CI], 1.09-1.71, Ptrend=.005). The glycemic load (an indicator of a global dietary insulin demand) was also positively associated with diabetes (RR=1.47; 95% CI, 1.16-1.86, Ptrend=.003). Cereal fiber intake was inversely associated with risk of diabetes when comparing the extreme quintiles (RR=0.72,95% CI, 0.58-0.90, Ptrend=.001). The combination of a high glycemic load and a low cereal fiber intake further increased the risk of diabetes (RR=2.50, 95% CI, 1.14-5.51) when compared with a low glycemic load and high cereal fiber intake.Conclusions. —Our results support the hypothesis that diets with a high glycemic load and a low cereal fiber content increase risk of diabetes in women. Further, they suggest that grains should be consumed in a minimally refined form to reduce the incidence of diabetes.
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The dark pigmentation of Aureobasidium pullulans is due to melanin that stains the walls and may be heavily encrusted on the surface of older cells. The pigment granules can be shaken off ultrasonically. The melanin is quite impervious to ultraviolet light. Most strains of A. pullulans observed secrete a viscous "mucin" that encloses hyphae and spores in a matrix. In both hyphae and yeastlike blastospores, cross walls develop centripetally, and in many cases a pore is left in the cross wall, rendering possible protoplasmic movement and a heterokaryotic condition, which may account for the variability of the species. These wall pores are not like those found in Basidiomycetes. The blastospores contain droplets of lipid, and usually have but one nucleus though the few larger spores may have two or rarely three nuclei. The blastospores are not borne on stipules but bud from the parent cell in a manner similar to yeasts and leave behind a bud scar.
Article
The reaction of glucoamylase with starch granules from seven botanical sources (waxy maize, maize, barley, tapioca, amylomaize-7, shoti, and potato) and with four potato starches modified with acid in four types of alcohols (methanol, ethanol, 2-propanol, and 1-butanol) were studied using three concentrations of enzyme (2, 20, and 200 units mL−1). The kinetics of the formation of d-glucose were followed over 32 h for the three enzyme concentrations. The starches showed a wide degree of variance in their susceptibility to enzyme hydrolysis. They divided into three groups: waxy maize starch was the most susceptible being converted into 50, 95, and 98% d-glucose in 32 h for the three concentrations of enzyme, respectively; an intermediate group (barley, maize, and tapioca starches) was converted into 10–15, 60, and 75–80% d-glucose in 32 h for the three concentrations of enzyme, respectively; and the third and least susceptible group (amylomaize-7, shoti, and potato starches) was converted into 2–8, 9–16, and 13–21% d-glucose in 32 h for the three concentrations of enzyme, respectively. The percent conversion for the modified potato starches was proportional to the amount of enzyme and the degree of modification. The 100X (200 U mL−1) amount of enzyme gave 13, 17, 21 and 27% d-glucose in 32 h for potato starch modified in the four alcohols, respectively.
Article
BACKGROUND:In vitro starch digestibility tests are useful for the prediction of glycaemic index (GI). However, there are no internationally recognised methods and no one method has been found to be suitable for all food types. This study compared six in vitro methods, using four grain foods, including those with a varied particle size and soluble fibre content. Method variations included using chewing or mincing, mincing with or without amylase and incubation in a restricted versus non-restricted system. Hydrolysis index (HI) values, calculated from the starch digestibility curves and GI prediction equations were used to compare the in vitro results to GI.RESULTS: HI values for five of the six methods ranked all foods in the same order as the GI values. Using a GI prediction equation (predicted GIHI) the mincing (without amylase) non-restricted method had the smallest standard error of prediction between the predicted GIHI and GI values. This method was then validated using 14 grain foods and demonstrated a significant correlation (r = 0.93, P < 0.01) between the in vitro starch digestibility and reported GI responses.CONCLUSIONS: The non-restricted mincing method showed good potential as a new in vitro starch digestibility method for predicting GI in grain foods. Copyright © 2007 Society of Chemical Industry
Article
The structure of human pancreatic α-amylase has been determined to 1.8 Å resolution using X-ray diffraction techniques. This enzyme is found to be composed of three structural domains. The largest is Domain A (residues 1–99, 169–404), which forms a central eight-stranded parallel β-barrel, to one end of which are located the active site residues Asp 197, Glu 233, and Asp 300. Also found in this vicinity is a bound chloride ion that forms ligand interactions to Arg 195, Asn 298, and Arg 337. Domain B is the smallest (residues 100–168) and serves to form a calcium binding site against the wall of the β-barrel of Domain A. Protein groups making ligand interactions to this calcium include Asn 100, Arg 158, Asp 167, and His 201. Domain C (residues 405–496) is made up of anti-parallel β-structure and is only loosely associated with Domains A and B. It is notable that the N-terminal glutamine residue of human pancreatic α-amylase undergoes a posttranslational modification to form a stable pyrrolidone derivative that may provide protection against other digestive enzymes. Structure-based comparisons of human pancreatic α-amylase with functionally related enzymes serve to emphasize three points. Firstly, despite this approach facilitating primary sequence alignments with respect to the numerous insertions and deletions present, overall there is only ∼15% sequence homology between the mammalian and fungal α-amylases. Secondly, in contrast, these same studies indicate that significant structural homology is present and of the order of ∼70%. Thirdly, the positioning of Domain C can vary considerably between α-amylases. In terms of the more closely related porcine enzyme, there are four regions of polypeptide chain (residues 237–250, 304–310, 346–354, and 458–461) with significantly different conformations from those in human pancreatic α-amylase. At least two of these could play a role in observed differential substrate and cleavage pattern specificities between these enzymes. Similarly, amino acid differences between human pancreatic and salivary α-amylases have been localized and a number of these occur in the vicinity of the active site.
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An in vitro procedure to measure the rate of starch digestion in starchy common foodstuffs was developed. A first-order equation that rules the hydrolytic process was found: CC∞ (1−e−kt). Besides an in vivo assay, to calculate the glycemic index (GI), was carried out on thirty healthy volunteers. This is a simple in vitro method that could be used to estimate the metabolic glycemic response to a food. The best correlated value with in vivo glycemic responses was the percentage of starch hydrolysis at 90 min (r= 0.909, p≤0.05, GI1 = 39.21 + 0.803(H90)).
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The prognosis of patients with acute myocardial infarction (MI), according to the new criteria for impaired fasting glucose (IFG) (FG 100-126 mg/dl), has not been evaluated. A total of 2353 patients with acute MI and surviving at d 5 after admission were analyzed for short-term morbidity and mortality. FG was obtained at d 4 and 5. Patients were classified as diabetes mellitus (known diabetes or FG > or = 126 mg/dl), high IFG (110 < or = FG < 126 mg/dl), low IFG (100 < or = FG < 110 mg/dl), and normal fasting glucose (NFG) (FG < 100 mg/dl). Among the 2353 patients, 968 (41%) had diabetes mellitus, 262 (11%) had high IFG, 332 (14%) had low IFG, and 791 (34%) had NFG. Compared with NFG patients, 30-d cardiovascular mortality was increased in high but not low IFG subjects. In-hospital heart failure was increased in high IFG subjects (42 vs. 20% for NFG, P < 0.0001) but not low IFG subjects (21 vs. 20%). High IFG, but not low IFG, was an independent factor associated with 30-d cardiovascular mortality [odds ratio 2.33 (1.55-3.47)] and in-hospital heart failure [odds ratio 1.70 (1.36-2.07)]. The optimal threshold levels of FG on the receiver-operating characteristic curves were 114 and 112 mg/dl to predict mortality and in-hospital heart failure, respectively. The present study, based on a nonselected cohort of MI patients, underscores the high prevalence of IFG (25%) and highlights the clinical relevance of 110 mg/dl, but not 100 mg/dl, as a cutoff value to define the risk for worse outcome.
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Article
The glycaemic index (GI) is an in vivo measurement based on the glycaemic response to carbohydrate-containing foods, and allows foods to be ranked on the basis of the rate of digestion and absorption of the carbohydrates that they contain. GI values are normalized to a reference amount of available carbohydrate and do no reflect the amounts of carbohydrate normally present in foods; for example, a food with a low content of carbohydrates will have a high GI value if that carbohydrate is digested and absorbed rapidly in the human small intestine. This is potentially confusing for a person wishing to control his or her blood glucose levels by the choice of foods. The rate and extent of starch digestion in vitro has been measured using a technique that classifies starch into three major fractions: rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). In addition, this technique gives a value for rapidly available glucose (RAG), which includes RDS, free glucose and the glucose moiety of sucrose. When the values for thirty-nine foods were expressed on the basis of the available carbohydrate content of these foods, highly significant (P < 0.001) positive correlations were observed between GI and both RDS and RAG. The measurement of RAG in vitro provides values for direct calculation of the amount of glucose likely to be rapidly absorbed in the human small intestine and, thus, to influence blood glucose and insulin levels. These values can be used to compare foods, as eaten, on an equal-weight basis. Food-table RAG values would allow simple calculation of the total amount of RAG provided by single foods, by whole meals and by whole diets. Studies are planned in which RAG and the glycaemic response in man will be measured for identical food products.
Article
To examine prospectively the relationship between glycemic diets, low fiber intake, and risk of non-insulin-dependent diabetes mellitus. Cohort study. In 1986, a total of 65173 US women 40 to 65 years of age and free from diagnosed cardiovascular disease, cancer, and diabetes completed a detailed dietary questionnaire from which we calculated usual intake of total and specific sources of dietary fiber, dietary glycemic index, and glycemic load. Non-insulin-dependent diabetes mellitus. During 6 years of follow-up, 915 incident cases of diabetes were documented. The dietary glycemic index was positively associated with risk of diabetes after adjustment for age, body mass index, smoking, physical activity, family history of diabetes, alcohol and cereal fiber intake, and total energy intake. Comparing the highest with the lowest quintile, the relative risk (RR) of diabetes was 1.37 (95% confidence interval [CI], 1.09-1.71, P trend=.005). The glycemic load (an indicator of a global dietary insulin demand) was also positively associated with diabetes (RR= 1.47; 95% CI, 1.16-1.86, P trend=.003). Cereal fiber intake was inversely associated with risk of diabetes when comparing the extreme quintiles (RR=0.72, 95% CI, 0.58-0.90, P trend=.001). The combination of a high glycemic load and a low cereal fiber intake further increased the risk of diabetes (RR=2.50, 95% CI, 1.14-5.51) when compared with a low glycemic load and high cereal fiber intake. Our results support the hypothesis that diets with a high glycemic load and a low cereal fiber content increase risk of diabetes in women. Further, they suggest that grains should be consumed in a minimally refined form to reduce the incidence of diabetes.
Article
To determine the plasma glucose and insulin responses of various doses of glucose, sucrose, fructose and white bread in normal human subjects. Plasma glucose and insulin were measured before and at various times after 8 subjects ate 13 different test meals in randomized order on separate days after an overnight fast. Test meals consisted of 500 ml of tea or water to which was added either nothing, 25, 50, or 100 g of glucose or sucrose, 25 or 50 g fructose, 50 g glucose plus 50 g fructose, or a 25, 50 or 100 g carbohydrate portion of white bread. The glycaemic (GI) and insulinaemic index (II) values of the sugars were calculated by expressing the incremental areas under the plasma glucose and insulin curves (AUC) after glucose, sucrose and fructose as a percentage of the respective AUC after white bread containing the same amount of carbohydrate. University teaching hospital clinical nutrition centre. Lean, normal subjects (4 male, 4 female) 21-33 y of age. Plasma insulin responses increased nearly linearly as carbohydrate intake increased from 0 to 100 g, but glycaemic responses increased by only 68% and 38% as carbohydrate intake increased from 25 to 50 g and 50 to 100g, respectively. The GI and II values of glucose, 149+/-16 and 147+/-18, respectively, were significantly greater than those of bread (100; P<0.05), while the values for fructose, 16+/-4 and 22+/-3 were significantly less than those of bread (P<0.001). GI values did not differ significantly from II values. It is concluded that, in normal subjects, as carbohydrate intake is increased from 0 to 100 g, plasma insulin responses increase at a greater rate than plasma glucose responses. The insulinaemic responses elicited by glucose, sucrose or fructose are similar to those that would be expected from a starchy food with the same glycaemic index.
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Intervention strategies aimed at reducing the prevalence of nutrition-related diseases, including designing nutrition policies and nutrition education and assistance programs, require effective monitoring of what Americans are eating. Nutrient reference data from the third National Health and Nutrition Examination Survey provide essential information to achieve these goals. Mean and median iron intakes were adequate in males of all race-ethnic groups but were generally low in females and young children. Mean and median calcium intakes were also higher in males than in females and were lower than recommendations in adolescents and in women of all ages. Mean sodium intakes for all age, sex, and race-ethnic groups exceeded the minimum requirements of healthy persons and were higher in non-Hispanic black children and adolescents than in non-Hispanic white and Mexican American children and adolescents. Mean fiber intakes also did not meet recommendations in most subgroups and were higher in Mexican American adults followed by non-Hispanic white adults and non-Hispanic black adults. Further research is planned to compare the food sources of energy and nutrients consumed by different population groups in NHANES III to similar results from earlier nation surveys. NHANES III, Phase 2 (1991-94) recalls were collected using the same dietary method as those collected in Phase 1 (1988-91), and other analyses will compare findings from both phases of NHANES III.
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The issue of whether glucose concentrations below the diabetic threshold may be predictive of increased cardiovascular risk has not yet been fully elucidated. The current study evaluates the prognosis of nondiabetic patients with ischemic heart disease (IHD) and impaired fasting glucose (IFG) over a 7.7-year follow-up period. A total of 11,853 patients with documented coronary artery disease aged between 45 and 74 years were examined. Patients were divided into 3 groups on the basis of their fasting blood glucose levels at screening: nondiabetic individuals, patients with IFG, and undiagnosed diabetic patients. Patients who were on any type of pharmacologic antidiabetic treatment were excluded from the study. Mortality rates were assessed separately for each group. The population comprised 9773 nondiabetic patients (82.4%, glucose up to 109 mg/dL), 1258 patients with IFG levels (10.6%, glucose 110-125 mg/dL), and 822 diabetic subjects (7%, glucose > or =126 mg/dL). Patients were followed up from 6.2 to 9.0 years (mean follow-up period 7.7 +/- 1.5 years). Crude mortality was lower in the nondiabetic subjects than in the 2 other groups. All-cause mortality in the nondiabetic group was 14.3% compared to 20.1% in patients with IFG and 24.3% in the undiagnosed (P <.001). Multivariate adjustment showed the lowest mortality in nondiabetic subjects, who exhibited a survival rate of 0.86 at the end of the follow-up, whereas the lowest survival-0.75-was seen among undiagnosed diabetic patients (P =.0001). An intermediate value of 0.78 was documented for patients with IFG (P <.01). After multivariate analysis, with nondiabetic patients as the reference group, IFG was identified as a consistent predictor of increased all-cause and IHD mortality with hazard ratios of 1.39 (95% confidence interval 1.21-1.59) and 1.29 (95% confidence interval 1.01-1.64), respectively. The main finding of this study is the substantially increased mortality rate among nondiabetic coronary patients with IFG, who had fasting glucose levels markedly lower than hitherto acknowledged as defining overt diabetes.
Article
A robust and reliable method was developed to measure resistant starch (RS), i.e., starch that enters the large intestine. In vivo conditions were reflected as much as possible while a user-friendly format was maintained. Parameters investigated included a-amylase concentration, pH of incubation, maltose inhibition of alpha-amylase, the need for amyloglucosidase inclusion, the effect of shaking and stirring on determined values, and problems in recovering and analyzing the RS-containing pellet. The RS values obtained were in good agreement with published in vivo data. An interlaboratory evaluation of the method has been completed (First Action Method 2002.02).
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Over the past two decades, cholesterol-lowering drugs have proven to be effective and have been found to significantly reduce the risk of coronary heart disease (CHD). However, diet and lifestyle factors are still recognized as the first line of intervention for CHD risk reduction by the National Cholesterol Education Program and the American Heart Association, which now advocate use of viscous fibers and plant sterols, and soy protein and nuts, respectively. In a series of metabolically controlled studies, we have combined these four cholesterol-lowering dietary components in the same diet (ie, a dietary portfolio of cholesterol-lowering foods) in an attempt to maximize low-density lipoprotein cholesterol reduction. We have found that the portfolio diet reduced low-density lipoprotein cholesterol by approximately 30% and produced clinically significant reductions in CHD risk. These reductions were the same as found with a starting dose of a first-generation statin drug.
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Action of human small intestinal brush border carbohydrate digesting enzymes is thought to involve only final hydrolysis reactions of oligosaccharides to monosaccharides. In vitro starch digestibility assays use fungal amyloglucosidase to provide this function. In this study, recombinant N-terminal subunit enzyme of human small intestinal maltase-glucoamylase (rhMGAM-N) was used to explore digestion of native starches from different botanical sources. The susceptibilities to enzyme hydrolysis varied among the starches. The rate and extent of hydrolysis of amylomaize-5 and amylomaize-7 into glucose were greater than for other starches. Such was not observed with fungal amyloglucosidase or pancreatic alpha-amylase. The degradation of native starch granules showed a surface furrowed pattern in random, radial, or tree-like arrangements that differed substantially from the erosion patterns of amyloglucosidase or alpha-amylase. The evidence of raw starch granule degradation with rhMGAM-N indicates that pancreatic alpha-amylase hydrolysis is not a requirement for native starch digestion in the human small intestine.
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We sought to determine whether impaired fasting glucose (IFG) predicts cardiovascular disease (CVD) events. It is unclear which glucose threshold should define prediabetes. We compared the 1997 and 2003 American Diabetes Association (ADA) definitions of IFG to predict CVD. Framingham offspring participants free of CVD, categorized by the 1997 ADA IFG definition (fasting plasma glucose 110 to 125 mg/dl; 6.1 to 6.9 mmol/l) or the 2003 definition (100 to 125 mg/dl; 5.6 to 6.9 mmol/l), were followed from 1983 to 2004. Pooled logistic regression was used to calculate multivariable-adjusted odds ratios (ORs) for incident coronary heart disease (CHD; 291 events) or CVD (423 events). Four-year CHD event rates among women were 1.3% (100 to 109 mg/dl), 2.3% (110 to 125 mg/dl), and 2.9% (diabetes); whereas corresponding rates in men were 2.9%, 3.0%, and 8.7%. For the 2003 IFG definition, the OR for CHD among women was 1.7 (95% confidence interval [CI] 1.0 to 3.0, p = 0.048), whereas for the 1997 IFG definition, the OR for CHD in women was 2.2 (95% CI 1.1 to 4.4, p = 0.02), which was almost as high as for women with diabetes (OR 2.5, 95% CI 1.2 to 5.2, p =